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2017-09-06mm, THP, swap: support splitting THP for THP swap outHuang Ying
After adding swapping out support for THP (Transparent Huge Page), it is possible that a THP in swap cache (partly swapped out) need to be split. To split such a THP, the swap cluster backing the THP need to be split too, that is, the CLUSTER_FLAG_HUGE flag need to be cleared for the swap cluster. The patch implemented this. And because the THP swap writing needs the THP keeps as huge page during writing. The PageWriteback flag is checked before splitting. Link: http://lkml.kernel.org/r/20170724051840.2309-8-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Michal Hocko <mhocko@kernel.org> Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c] Cc: Vishal L Verma <vishal.l.verma@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-06mm, THP, swap: make reuse_swap_page() works for THP swapped outHuang Ying
After supporting to delay THP (Transparent Huge Page) splitting after swapped out, it is possible that some page table mappings of the THP are turned into swap entries. So reuse_swap_page() need to check the swap count in addition to the map count as before. This patch done that. In the huge PMD write protect fault handler, in addition to the page map count, the swap count need to be checked too, so the page lock need to be acquired too when calling reuse_swap_page() in addition to the page table lock. [ying.huang@intel.com: silence a compiler warning] Link: http://lkml.kernel.org/r/87bmnzizjy.fsf@yhuang-dev.intel.com Link: http://lkml.kernel.org/r/20170724051840.2309-4-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Michal Hocko <mhocko@kernel.org> Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c] Cc: Vishal L Verma <vishal.l.verma@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-06mm/huge_memory.c: constify attribute_group structuresArvind Yadav
attribute_group are not supposed to change at runtime. All functions working with attribute_group provided by <linux/sysfs.h> work with const attribute_group. So mark the non-const structs as const. Link: http://lkml.kernel.org/r/1501157240-3876-1-git-send-email-arvind.yadav.cs@gmail.com Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-25Merge branch 'linus' into locking/core, to pick up fixesIngo Molnar
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-18mm, oom: fix potential data corruption when oom_reaper races with writerMichal Hocko
Wenwei Tao has noticed that our current assumption that the oom victim is dying and never doing any visible changes after it dies, and so the oom_reaper can tear it down, is not entirely true. __task_will_free_mem consider a task dying when SIGNAL_GROUP_EXIT is set but do_group_exit sends SIGKILL to all threads _after_ the flag is set. So there is a race window when some threads won't have fatal_signal_pending while the oom_reaper could start unmapping the address space. Moreover some paths might not check for fatal signals before each PF/g-u-p/copy_from_user. We already have a protection for oom_reaper vs. PF races by checking MMF_UNSTABLE. This has been, however, checked only for kernel threads (use_mm users) which can outlive the oom victim. A simple fix would be to extend the current check in handle_mm_fault for all tasks but that wouldn't be sufficient because the current check assumes that a kernel thread would bail out after EFAULT from get_user*/copy_from_user and never re-read the same address which would succeed because the PF path has established page tables already. This seems to be the case for the only existing use_mm user currently (virtio driver) but it is rather fragile in general. This is even more fragile in general for more complex paths such as generic_perform_write which can re-read the same address more times (e.g. iov_iter_copy_from_user_atomic to fail and then iov_iter_fault_in_readable on retry). Therefore we have to implement MMF_UNSTABLE protection in a robust way and never make a potentially corrupted content visible. That requires to hook deeper into the PF path and check for the flag _every time_ before a pte for anonymous memory is established (that means all !VM_SHARED mappings). The corruption can be triggered artificially (http://lkml.kernel.org/r/201708040646.v746kkhC024636@www262.sakura.ne.jp) but there doesn't seem to be any real life bug report. The race window should be quite tight to trigger most of the time. Link: http://lkml.kernel.org/r/20170807113839.16695-3-mhocko@kernel.org Fixes: aac453635549 ("mm, oom: introduce oom reaper") Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Wenwei Tao <wenwei.tww@alibaba-inc.com> Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Andrea Argangeli <andrea@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-11mm, locking: Fix up flush_tlb_pending() related merge in do_huge_pmd_numa_page()Peter Zijlstra
Merge commit: 040cca3ab2f6 ("Merge branch 'linus' into locking/core, to resolve conflicts") overlooked the fact that do_huge_pmd_numa_page() now does two TLB flushes. Commit: 8b1b436dd1cc ("mm, locking: Rework {set,clear,mm}_tlb_flush_pending()") and commit: a9b802500ebb ("Revert "mm: numa: defer TLB flush for THP migration as long as possible"") Both moved the TLB flush around but slightly different, the end result being that what was one became two. Clean this up. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Rik van Riel <riel@redhat.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-11Merge branch 'linus' into locking/core, to resolve conflictsIngo Molnar
Conflicts: include/linux/mm_types.h mm/huge_memory.c I removed the smp_mb__before_spinlock() like the following commit does: 8b1b436dd1cc ("mm, locking: Rework {set,clear,mm}_tlb_flush_pending()") and fixed up the affected commits. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10Revert "mm: numa: defer TLB flush for THP migration as long as possible"Nadav Amit
While deferring TLB flushes is a good practice, the reverted patch caused pending TLB flushes to be checked while the page-table lock is not taken. As a result, in architectures with weak memory model (PPC), Linux may miss a memory-barrier, miss the fact TLB flushes are pending, and cause (in theory) a memory corruption. Since the alternative of using smp_mb__after_unlock_lock() was considered a bit open-coded, and the performance impact is expected to be small, the previous patch is reverted. This reverts b0943d61b8fa ("mm: numa: defer TLB flush for THP migration as long as possible"). Link: http://lkml.kernel.org/r/20170802000818.4760-4-namit@vmware.com Signed-off-by: Nadav Amit <namit@vmware.com> Suggested-by: Mel Gorman <mgorman@suse.de> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Tony Luck <tony.luck@intel.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-10mm, locking: Rework {set,clear,mm}_tlb_flush_pending()Peter Zijlstra
Commit: af2c1401e6f9 ("mm: numa: guarantee that tlb_flush_pending updates are visible before page table updates") added smp_mb__before_spinlock() to set_tlb_flush_pending(). I think we can solve the same problem without this barrier. If instead we mandate that mm_tlb_flush_pending() is used while holding the PTL we're guaranteed to observe prior set_tlb_flush_pending() instances. For this to work we need to rework migrate_misplaced_transhuge_page() a little and move the test up into do_huge_pmd_numa_page(). NOTE: this relies on flush_tlb_range() to guarantee: (1) it ensures that prior page table updates are visible to the page table walker and (2) it ensures that subsequent memory accesses are only made visible after the invalidation has completed This is required for architectures that implement TRANSPARENT_HUGEPAGE (arc, arm, arm64, mips, powerpc, s390, sparc, x86) or otherwise use mm_tlb_flush_pending() in their page-table operations (arm, arm64, x86). This appears true for: - arm (DSB ISB before and after), - arm64 (DSB ISHST before, and DSB ISH after), - powerpc (PTESYNC before and after), - s390 and x86 TLB invalidate are serializing instructions But I failed to understand the situation for: - arc, mips, sparc Now SPARC64 is a wee bit special in that flush_tlb_range() is a no-op and it flushes the TLBs using arch_{enter,leave}_lazy_mmu_mode() inside the PTL. It still needs to guarantee the PTL unlock happens _after_ the invalidate completes. Vineet, Ralf and Dave could you guys please have a look? Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Rik van Riel <riel@redhat.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-06mm, THP, swap: check whether THP can be split firstlyHuang Ying
To swap out THP (Transparent Huage Page), before splitting the THP, the swap cluster will be allocated and the THP will be added into the swap cache. But it is possible that the THP cannot be split, so that we must delete the THP from the swap cache and free the swap cluster. To avoid that, in this patch, whether the THP can be split is checked firstly. The check can only be done racy, but it is good enough for most cases. With the patch, the swap out throughput improves 3.6% (from about 4.16GB/s to about 4.31GB/s) in the vm-scalability swap-w-seq test case with 8 processes. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case creates 8 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used up. Link: http://lkml.kernel.org/r/20170515112522.32457-5-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> [for can_split_huge_page()] Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06mm, THP, swap: delay splitting THP during swap outHuang Ying
Patch series "THP swap: Delay splitting THP during swapping out", v11. This patchset is to optimize the performance of Transparent Huge Page (THP) swap. Recently, the performance of the storage devices improved so fast that we cannot saturate the disk bandwidth with single logical CPU when do page swap out even on a high-end server machine. Because the performance of the storage device improved faster than that of single logical CPU. And it seems that the trend will not change in the near future. On the other hand, the THP becomes more and more popular because of increased memory size. So it becomes necessary to optimize THP swap performance. The advantages of the THP swap support include: - Batch the swap operations for the THP to reduce lock acquiring/releasing, including allocating/freeing the swap space, adding/deleting to/from the swap cache, and writing/reading the swap space, etc. This will help improve the performance of the THP swap. - The THP swap space read/write will be 2M sequential IO. It is particularly helpful for the swap read, which are usually 4k random IO. This will improve the performance of the THP swap too. - It will help the memory fragmentation, especially when the THP is heavily used by the applications. The 2M continuous pages will be free up after THP swapping out. - It will improve the THP utilization on the system with the swap turned on. Because the speed for khugepaged to collapse the normal pages into the THP is quite slow. After the THP is split during the swapping out, it will take quite long time for the normal pages to collapse back into the THP after being swapped in. The high THP utilization helps the efficiency of the page based memory management too. There are some concerns regarding THP swap in, mainly because possible enlarged read/write IO size (for swap in/out) may put more overhead on the storage device. To deal with that, the THP swap in should be turned on only when necessary. For example, it can be selected via "always/never/madvise" logic, to be turned on globally, turned off globally, or turned on only for VMA with MADV_HUGEPAGE, etc. This patchset is the first step for the THP swap support. The plan is to delay splitting THP step by step, finally avoid splitting THP during the THP swapping out and swap out/in the THP as a whole. As the first step, in this patchset, the splitting huge page is delayed from almost the first step of swapping out to after allocating the swap space for the THP and adding the THP into the swap cache. This will reduce lock acquiring/releasing for the locks used for the swap cache management. With the patchset, the swap out throughput improves 15.5% (from about 3.73GB/s to about 4.31GB/s) in the vm-scalability swap-w-seq test case with 8 processes. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case creates 8 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used up. This patch (of 5): In this patch, splitting huge page is delayed from almost the first step of swapping out to after allocating the swap space for the THP (Transparent Huge Page) and adding the THP into the swap cache. This will batch the corresponding operation, thus improve THP swap out throughput. This is the first step for the THP swap optimization. The plan is to delay splitting the THP step by step and avoid splitting the THP finally. In this patch, one swap cluster is used to hold the contents of each THP swapped out. So, the size of the swap cluster is changed to that of the THP (Transparent Huge Page) on x86_64 architecture (512). For other architectures which want such THP swap optimization, ARCH_USES_THP_SWAP_CLUSTER needs to be selected in the Kconfig file for the architecture. In effect, this will enlarge swap cluster size by 2 times on x86_64. Which may make it harder to find a free cluster when the swap space becomes fragmented. So that, this may reduce the continuous swap space allocation and sequential write in theory. The performance test in 0day shows no regressions caused by this. In the future of THP swap optimization, some information of the swapped out THP (such as compound map count) will be recorded in the swap_cluster_info data structure. The mem cgroup swap accounting functions are enhanced to support charge or uncharge a swap cluster backing a THP as a whole. The swap cluster allocate/free functions are added to allocate/free a swap cluster for a THP. A fair simple algorithm is used for swap cluster allocation, that is, only the first swap device in priority list will be tried to allocate the swap cluster. The function will fail if the trying is not successful, and the caller will fallback to allocate a single swap slot instead. This works good enough for normal cases. If the difference of the number of the free swap clusters among multiple swap devices is significant, it is possible that some THPs are split earlier than necessary. For example, this could be caused by big size difference among multiple swap devices. The swap cache functions is enhanced to support add/delete THP to/from the swap cache as a set of (HPAGE_PMD_NR) sub-pages. This may be enhanced in the future with multi-order radix tree. But because we will split the THP soon during swapping out, that optimization doesn't make much sense for this first step. The THP splitting functions are enhanced to support to split THP in swap cache during swapping out. The page lock will be held during allocating the swap cluster, adding the THP into the swap cache and splitting the THP. So in the code path other than swapping out, if the THP need to be split, the PageSwapCache(THP) will be always false. The swap cluster is only available for SSD, so the THP swap optimization in this patchset has no effect for HDD. [ying.huang@intel.com: fix two issues in THP optimize patch] Link: http://lkml.kernel.org/r/87k25ed8zo.fsf@yhuang-dev.intel.com [hannes@cmpxchg.org: extensive cleanups and simplifications, reduce code size] Link: http://lkml.kernel.org/r/20170515112522.32457-2-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Andrew Morton <akpm@linux-foundation.org> [for config option] Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> [for changes in huge_memory.c and huge_mm.h] Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06thp, mm: fix crash due race in MADV_FREE handlingKirill A. Shutemov
Reinette reported the following crash: BUG: Bad page state in process log2exe pfn:57600 page:ffffea00015d8000 count:0 mapcount:0 mapping: (null) index:0x20200 flags: 0x4000000000040019(locked|uptodate|dirty|swapbacked) raw: 4000000000040019 0000000000000000 0000000000020200 00000000ffffffff raw: ffffea00015d8020 ffffea00015d8020 0000000000000000 0000000000000000 page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set bad because of flags: 0x1(locked) Modules linked in: rfcomm 8021q bnep intel_rapl x86_pkg_temp_thermal coretemp efivars btusb btrtl btbcm pwm_lpss_pci snd_hda_codec_hdmi btintel pwm_lpss snd_hda_codec_realtek snd_soc_skl snd_hda_codec_generic snd_soc_skl_ipc spi_pxa2xx_platform snd_soc_sst_ipc snd_soc_sst_dsp i2c_designware_platform i2c_designware_core snd_hda_ext_core snd_soc_sst_match snd_hda_intel snd_hda_codec mei_me snd_hda_core mei snd_soc_rt286 snd_soc_rl6347a snd_soc_core efivarfs CPU: 1 PID: 354 Comm: log2exe Not tainted 4.12.0-rc7-test-test #19 Hardware name: Intel corporation NUC6CAYS/NUC6CAYB, BIOS AYAPLCEL.86A.0027.2016.1108.1529 11/08/2016 Call Trace: bad_page+0x16a/0x1f0 free_pages_check_bad+0x117/0x190 free_hot_cold_page+0x7b1/0xad0 __put_page+0x70/0xa0 madvise_free_huge_pmd+0x627/0x7b0 madvise_free_pte_range+0x6f8/0x1150 __walk_page_range+0x6b5/0xe30 walk_page_range+0x13b/0x310 madvise_free_page_range.isra.16+0xad/0xd0 madvise_free_single_vma+0x2e4/0x470 SyS_madvise+0x8ce/0x1450 If somebody frees the page under us and we hold the last reference to it, put_page() would attempt to free the page before unlocking it. The fix is trivial reorder of operations. Dave said: "I came up with the exact same patch. For posterity, here's the test case, generated by syzkaller and trimmed down by Reinette: https://www.sr71.net/~dave/intel/log2.c And the config that helps detect this: https://www.sr71.net/~dave/intel/config-log2" Fixes: b8d3c4c3009d ("mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called") Link: http://lkml.kernel.org/r/20170628101249.17879-1-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Reinette Chatre <reinette.chatre@intel.com> Acked-by: Dave Hansen <dave.hansen@intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Huang Ying <ying.huang@intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-17mm: numa: avoid waiting on freed migrated pagesMark Rutland
In do_huge_pmd_numa_page(), we attempt to handle a migrating thp pmd by waiting until the pmd is unlocked before we return and retry. However, we can race with migrate_misplaced_transhuge_page(): // do_huge_pmd_numa_page // migrate_misplaced_transhuge_page() // Holds 0 refs on page // Holds 2 refs on page vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); /* ... */ if (pmd_trans_migrating(*vmf->pmd)) { page = pmd_page(*vmf->pmd); spin_unlock(vmf->ptl); ptl = pmd_lock(mm, pmd); if (page_count(page) != 2)) { /* roll back */ } /* ... */ mlock_migrate_page(new_page, page); /* ... */ spin_unlock(ptl); put_page(page); put_page(page); // page freed here wait_on_page_locked(page); goto out; } This can result in the freed page having its waiters flag set unexpectedly, which trips the PAGE_FLAGS_CHECK_AT_PREP checks in the page alloc/free functions. This has been observed on arm64 KVM guests. We can avoid this by having do_huge_pmd_numa_page() take a reference on the page before dropping the pmd lock, mirroring what we do in __migration_entry_wait(). When we hit the race, migrate_misplaced_transhuge_page() will see the reference and abort the migration, as it may do today in other cases. Fixes: b8916634b77bffb2 ("mm: Prevent parallel splits during THP migration") Link: http://lkml.kernel.org/r/1497349722-6731-2-git-send-email-will.deacon@arm.com Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Steve Capper <steve.capper@arm.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-08mm/huge_memory.c: deposit a pgtable for DAX PMD faults when requiredOliver O'Halloran
Although all architectures use a deposited page table for THP on anonymous VMAs, some architectures (s390 and powerpc) require the deposited storage even for file backed VMAs due to quirks of their MMUs. This patch adds support for depositing a table in DAX PMD fault handling path for archs that require it. Other architectures should see no functional changes. Link: http://lkml.kernel.org/r/20170411174233.21902-3-oohall@gmail.com Signed-off-by: Oliver O'Halloran <oohall@gmail.com> Cc: Reza Arbab <arbab@linux.vnet.ibm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: linux-nvdimm@ml01.01.org Cc: Oliver O'Halloran <oohall@gmail.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-08mm/huge_memory.c: use zap_deposited_table() moreOliver O'Halloran
Depending on the flags of the PMD being zapped there may or may not be a deposited pgtable to be freed. In two of the three cases this is open coded while the third uses the zap_deposited_table() helper. This patch converts the others to use the helper to clean things up a bit. Link: http://lkml.kernel.org/r/20170411174233.21902-2-oohall@gmail.com Cc: Reza Arbab <arbab@linux.vnet.ibm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: linux-nvdimm@ml01.01.org Cc: Oliver O'Halloran <oohall@gmail.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-03mm: make ttu's return booleanMinchan Kim
try_to_unmap() returns SWAP_SUCCESS or SWAP_FAIL so it's suitable for boolean return. This patch changes it. Link: http://lkml.kernel.org/r/1489555493-14659-8-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-03mm: reclaim MADV_FREE pagesShaohua Li
When memory pressure is high, we free MADV_FREE pages. If the pages are not dirty in pte, the pages could be freed immediately. Otherwise we can't reclaim them. We put the pages back to anonumous LRU list (by setting SwapBacked flag) and the pages will be reclaimed in normal swapout way. We use normal page reclaim policy. Since MADV_FREE pages are put into inactive file list, such pages and inactive file pages are reclaimed according to their age. This is expected, because we don't want to reclaim too many MADV_FREE pages before used once pages. Based on Minchan's original patch [minchan@kernel.org: clean up lazyfree page handling] Link: http://lkml.kernel.org/r/20170303025237.GB3503@bbox Link: http://lkml.kernel.org/r/14b8eb1d3f6bf6cc492833f183ac8c304e560484.1487965799.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-03mm: move MADV_FREE pages into LRU_INACTIVE_FILE listShaohua Li
madv()'s MADV_FREE indicate pages are 'lazyfree'. They are still anonymous pages, but they can be freed without pageout. To distinguish these from normal anonymous pages, we clear their SwapBacked flag. MADV_FREE pages could be freed without pageout, so they pretty much like used once file pages. For such pages, we'd like to reclaim them once there is memory pressure. Also it might be unfair reclaiming MADV_FREE pages always before used once file pages and we definitively want to reclaim the pages before other anonymous and file pages. To speed up MADV_FREE pages reclaim, we put the pages into LRU_INACTIVE_FILE list. The rationale is LRU_INACTIVE_FILE list is tiny nowadays and should be full of used once file pages. Reclaiming MADV_FREE pages will not have much interfere of anonymous and active file pages. And the inactive file pages and MADV_FREE pages will be reclaimed according to their age, so we don't reclaim too many MADV_FREE pages too. Putting the MADV_FREE pages into LRU_INACTIVE_FILE_LIST also means we can reclaim the pages without swap support. This idea is suggested by Johannes. This patch doesn't move MADV_FREE pages to LRU_INACTIVE_FILE list yet to avoid bisect failure, next patch will do it. The patch is based on Minchan's original patch. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/2f87063c1e9354677b7618c647abde77b07561e5.1487965799.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-03mm: don't assume anonymous pages have SwapBacked flagShaohua Li
There are a few places the code assumes anonymous pages should have SwapBacked flag set. MADV_FREE pages are anonymous pages but we are going to add them to LRU_INACTIVE_FILE list and clear SwapBacked flag for them. The assumption doesn't hold any more, so fix them. Link: http://lkml.kernel.org/r/3945232c0df3dd6c4ef001976f35a95f18dcb407.1487965799.git.shli@fb.com Signed-off-by: Shaohua Li <shli@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-04-13thp: fix MADV_DONTNEED vs. MADV_FREE raceKirill A. Shutemov
Both MADV_DONTNEED and MADV_FREE handled with down_read(mmap_sem). It's critical to not clear pmd intermittently while handling MADV_FREE to avoid race with MADV_DONTNEED: CPU0: CPU1: madvise_free_huge_pmd() pmdp_huge_get_and_clear_full() madvise_dontneed() zap_pmd_range() pmd_trans_huge(*pmd) == 0 (without ptl) // skip the pmd set_pmd_at(); // pmd is re-established It results in MADV_DONTNEED skipping the pmd, leaving it not cleared. It violates MADV_DONTNEED interface and can result is userspace misbehaviour. Basically it's the same race as with numa balancing in change_huge_pmd(), but a bit simpler to mitigate: we don't need to preserve dirty/young flags here due to MADV_FREE functionality. [kirill.shutemov@linux.intel.com: Urgh... Power is special again] Link: http://lkml.kernel.org/r/20170303102636.bhd2zhtpds4mt62a@black.fi.intel.com Link: http://lkml.kernel.org/r/20170302151034.27829-4-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-04-13thp: fix MADV_DONTNEED vs. numa balancing raceKirill A. Shutemov
In case prot_numa, we are under down_read(mmap_sem). It's critical to not clear pmd intermittently to avoid race with MADV_DONTNEED which is also under down_read(mmap_sem): CPU0: CPU1: change_huge_pmd(prot_numa=1) pmdp_huge_get_and_clear_notify() madvise_dontneed() zap_pmd_range() pmd_trans_huge(*pmd) == 0 (without ptl) // skip the pmd set_pmd_at(); // pmd is re-established The race makes MADV_DONTNEED miss the huge pmd and don't clear it which may break userspace. Found by code analysis, never saw triggered. Link: http://lkml.kernel.org/r/20170302151034.27829-3-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-04-13thp: reduce indentation level in change_huge_pmd()Kirill A. Shutemov
Patch series "thp: fix few MADV_DONTNEED races" For MADV_DONTNEED to work properly with huge pages, it's critical to not clear pmd intermittently unless you hold down_write(mmap_sem). Otherwise MADV_DONTNEED can miss the THP which can lead to userspace breakage. See example of such race in commit message of patch 2/4. All these races are found by code inspection. I haven't seen them triggered. I don't think it's worth to apply them to stable@. This patch (of 4): Restructure code in preparation for a fix. Link: http://lkml.kernel.org/r/20170302151034.27829-2-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-04-08mm, thp: fix setting of defer+madvise thp defrag modeDavid Rientjes
Setting thp defrag mode of "defer+madvise" actually sets "defer" in the kernel due to the name similarity and the out-of-order way the string is checked in defrag_store(). Check the string in the correct order so that TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG is set appropriately for "defer+madvise". Fixes: 21440d7eb904 ("mm, thp: add new defer+madvise defrag option") Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1704051814420.137626@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-03-10Merge branch 'prep-for-5level'Linus Torvalds
Merge 5-level page table prep from Kirill Shutemov: "Here's relatively low-risk part of 5-level paging patchset. Merging it now will make x86 5-level paging enabling in v4.12 easier. The first patch is actually x86-specific: detect 5-level paging support. It boils down to single define. The rest of patchset converts Linux MMU abstraction from 4- to 5-level paging. Enabling of new abstraction in most cases requires adding single line of code in arch-specific code. The rest is taken care by asm-generic/. Changes to mm/ code are mostly mechanical: add support for new page table level -- p4d_t -- where we deal with pud_t now. v2: - fix build on microblaze (Michal); - comment for __ARCH_HAS_5LEVEL_HACK in kasan_populate_zero_shadow(); - acks from Michal" * emailed patches from Kirill A Shutemov <kirill.shutemov@linux.intel.com>: mm: introduce __p4d_alloc() mm: convert generic code to 5-level paging asm-generic: introduce <asm-generic/pgtable-nop4d.h> arch, mm: convert all architectures to use 5level-fixup.h asm-generic: introduce __ARCH_USE_5LEVEL_HACK asm-generic: introduce 5level-fixup.h x86/cpufeature: Add 5-level paging detection
2017-03-09mm/vmstats: add thp_split_pud event for clarityYisheng Xie
We added support for PUD-sized transparent hugepages, however we count the event "thp split pud" into thp_split_pmd event. To separate the event count of thp split pud from pmd, add a new event named thp_split_pud. Link: http://lkml.kernel.org/r/1488282380-5076-1-git-send-email-xieyisheng1@huawei.com Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Hugh Dickins <hughd@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: David Rientjes <rientjes@google.com> Cc: Hanjun Guo <guohanjun@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-03-09mm: convert generic code to 5-level pagingKirill A. Shutemov
Convert all non-architecture-specific code to 5-level paging. It's mostly mechanical adding handling one more page table level in places where we deal with pud_t. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<linux/sched/numa_balancing.h> We are going to split <linux/sched/numa_balancing.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/numa_balancing.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar
<linux/sched/coredump.h> We are going to split <linux/sched/coredump.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/coredump.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-02-24mm/thp/autonuma: use TNF flag instead of vm faultAneesh Kumar K.V
We are using the wrong flag value in task_numa_falt function. This can result in us doing wrong numa fault statistics update, because we update num_pages_migrate and numa_fault_locality etc based on the flag argument passed. Fixes: bae473a423 ("mm: introduce fault_env") Link: http://lkml.kernel.org/r/1487498395-9544-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@surriel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24mm/autonuma: let architecture override how the write bit should be stashed ↵Aneesh Kumar K.V
in a protnone pte. Patch series "Numabalancing preserve write fix", v2. This patch series address an issue w.r.t THP migration and autonuma preserve write feature. migrate_misplaced_transhuge_page() cannot deal with concurrent modification of the page. It does a page copy without following the migration pte sequence. IIUC, this was done to keep the migration simpler and at the time of implemenation we didn't had THP page cache which would have required a more elaborate migration scheme. That means thp autonuma migration expect the protnone with saved write to be done such that both kernel and user cannot update the page content. This patch series enables archs like ppc64 to do that. We are good with the hash translation mode with the current code, because we never create a hardware page table entry for a protnone pte. This patch (of 2): Autonuma preserves the write permission across numa fault to avoid taking a writefault after a numa fault (Commit: b191f9b106ea " mm: numa: preserve PTE write permissions across a NUMA hinting fault"). Architecture can implement protnone in different ways and some may choose to implement that by clearing Read/ Write/Exec bit of pte. Setting the write bit on such pte can result in wrong behaviour. Fix this up by allowing arch to override how to save the write bit on a protnone pte. [aneesh.kumar@linux.vnet.ibm.com: don't mark pte saved write in case of dirty_accountable] Link: http://lkml.kernel.org/r/1487942884-16517-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com [aneesh.kumar@linux.vnet.ibm.com: v3] Link: http://lkml.kernel.org/r/1487498625-10891-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1487050314-3892-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Michael Neuling <mikey@neuling.org> Cc: Rik van Riel <riel@surriel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Ellerman <michaele@au1.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24mm: convert try_to_unmap_one() to use page_vma_mapped_walk()Kirill A. Shutemov
For consistency, it worth converting all page_check_address() to page_vma_mapped_walk(), so we could drop the former. It also makes freeze_page() as we walk though rmap only once. Link: http://lkml.kernel.org/r/20170129173858.45174-8-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24mm: introduce page_vma_mapped_walk()Kirill A. Shutemov
Introduce a new interface to check if a page is mapped into a vma. It aims to address shortcomings of page_check_address{,_transhuge}. Existing interface is not able to handle PTE-mapped THPs: it only finds the first PTE. The rest lefted unnoticed. page_vma_mapped_walk() iterates over all possible mapping of the page in the vma. Link: http://lkml.kernel.org/r/20170129173858.45174-3-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24mm, x86: add support for PUD-sized transparent hugepagesMatthew Wilcox
The current transparent hugepage code only supports PMDs. This patch adds support for transparent use of PUDs with DAX. It does not include support for anonymous pages. x86 support code also added. Most of this patch simply parallels the work that was done for huge PMDs. The only major difference is how the new ->pud_entry method in mm_walk works. The ->pmd_entry method replaces the ->pte_entry method, whereas the ->pud_entry method works along with either ->pmd_entry or ->pte_entry. The pagewalk code takes care of locking the PUD before calling ->pud_walk, so handlers do not need to worry whether the PUD is stable. [dave.jiang@intel.com: fix SMP x86 32bit build for native_pud_clear()] Link: http://lkml.kernel.org/r/148719066814.31111.3239231168815337012.stgit@djiang5-desk3.ch.intel.com [dave.jiang@intel.com: native_pud_clear missing on i386 build] Link: http://lkml.kernel.org/r/148640375195.69754.3315433724330910314.stgit@djiang5-desk3.ch.intel.com Link: http://lkml.kernel.org/r/148545059381.17912.8602162635537598445.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Tested-by: Alexander Kapshuk <alexander.kapshuk@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jan Kara <jack@suse.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22mm, thp: add new defer+madvise defrag optionDavid Rientjes
There is no thp defrag option that currently allows MADV_HUGEPAGE regions to do direct compaction and reclaim while all other thp allocations simply trigger kswapd and kcompactd in the background and fail immediately. The "defer" setting simply triggers background reclaim and compaction for all regions, regardless of MADV_HUGEPAGE, which makes it unusable for our userspace where MADV_HUGEPAGE is being used to indicate the application is willing to wait for work for thp memory to be available. The "madvise" setting will do direct compaction and reclaim for these MADV_HUGEPAGE regions, but does not trigger kswapd and kcompactd in the background for anybody else. For reasonable usage, there needs to be a mesh between the two options. This patch introduces a fifth mode, "defer+madvise", that will do direct reclaim and compaction for MADV_HUGEPAGE regions and trigger background reclaim and compaction for everybody else so that hugepages may be available in the near future. A proposal to allow direct reclaim and compaction for MADV_HUGEPAGE regions as part of the "defer" mode, making it a very powerful setting and avoids breaking userspace, was offered: http://marc.info/?t=148236612700003 This additional mode is a compromise. A second proposal to allow both "defer" and "madvise" to be selected at the same time was also offered: http://marc.info/?t=148357345300001. This is possible, but there was a concern that it might break existing userspaces the parse the output of the defrag mode, so the fifth option was introduced instead. This patch also cleans up the helper function for storing to "enabled" and "defrag" since the former supports three modes while the latter supports five and triple_flag_store() was getting unnecessarily messy. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1701101614330.41805@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-24mm/huge_memory.c: respect FOLL_FORCE/FOLL_COW for thpKeno Fischer
In commit 19be0eaffa3a ("mm: remove gup_flags FOLL_WRITE games from __get_user_pages()"), the mm code was changed from unsetting FOLL_WRITE after a COW was resolved to setting the (newly introduced) FOLL_COW instead. Simultaneously, the check in gup.c was updated to still allow writes with FOLL_FORCE set if FOLL_COW had also been set. However, a similar check in huge_memory.c was forgotten. As a result, remote memory writes to ro regions of memory backed by transparent huge pages cause an infinite loop in the kernel (handle_mm_fault sets FOLL_COW and returns 0 causing a retry, but follow_trans_huge_pmd bails out immidiately because `(flags & FOLL_WRITE) && !pmd_write(*pmd)` is true. While in this state the process is stil SIGKILLable, but little else works (e.g. no ptrace attach, no other signals). This is easily reproduced with the following code (assuming thp are set to always): #include <assert.h> #include <fcntl.h> #include <stdint.h> #include <stdio.h> #include <string.h> #include <sys/mman.h> #include <sys/stat.h> #include <sys/types.h> #include <sys/wait.h> #include <unistd.h> #define TEST_SIZE 5 * 1024 * 1024 int main(void) { int status; pid_t child; int fd = open("/proc/self/mem", O_RDWR); void *addr = mmap(NULL, TEST_SIZE, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); assert(addr != MAP_FAILED); pid_t parent_pid = getpid(); if ((child = fork()) == 0) { void *addr2 = mmap(NULL, TEST_SIZE, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); assert(addr2 != MAP_FAILED); memset(addr2, 'a', TEST_SIZE); pwrite(fd, addr2, TEST_SIZE, (uintptr_t)addr); return 0; } assert(child == waitpid(child, &status, 0)); assert(WIFEXITED(status) && WEXITSTATUS(status) == 0); return 0; } Fix this by updating follow_trans_huge_pmd in huge_memory.c analogously to the update in gup.c in the original commit. The same pattern exists in follow_devmap_pmd. However, we should not be able to reach that check with FOLL_COW set, so add WARN_ONCE to make sure we notice if we ever do. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20170106015025.GA38411@juliacomputing.com Signed-off-by: Keno Fischer <keno@juliacomputing.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Greg Thelen <gthelen@google.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <keescook@chromium.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-10mm: pmd dirty emulation in page fault handlerMinchan Kim
Andreas reported [1] made a test in jemalloc hang in THP mode in arm64: http://lkml.kernel.org/r/mvmmvfy37g1.fsf@hawking.suse.de The problem is currently page fault handler doesn't supports dirty bit emulation of pmd for non-HW dirty-bit architecture so that application stucks until VM marked the pmd dirty. How the emulation work depends on the architecture. In case of arm64, when it set up pte firstly, it sets pte PTE_RDONLY to get a chance to mark the pte dirty via triggering page fault when store access happens. Once the page fault occurs, VM marks the pmd dirty and arch code for setting pmd will clear PTE_RDONLY for application to proceed. IOW, if VM doesn't mark the pmd dirty, application hangs forever by repeated fault(i.e., store op but the pmd is PTE_RDONLY). This patch enables pmd dirty-bit emulation for those architectures. [1] b8d3c4c3009d, mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called Fixes: b8d3c4c3009d ("mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called") Link: http://lkml.kernel.org/r/1482506098-6149-1-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Reported-by: Andreas Schwab <schwab@suse.de> Tested-by: Andreas Schwab <schwab@suse.de> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jason Evans <je@fb.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: <stable@vger.kernel.org> [4.5+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-10mm: get rid of __GFP_OTHER_NODEMichal Hocko
The flag was introduced by commit 78afd5612deb ("mm: add __GFP_OTHER_NODE flag") to allow proper accounting of remote node allocations done by kernel daemons on behalf of a process - e.g. khugepaged. After "mm: fix remote numa hits statistics" we do not need and actually use the flag so we can safely remove it because all allocations which are satisfied from their "home" node are accounted properly. [mhocko@suse.com: fix build] Link: http://lkml.kernel.org/r/20170106122225.GK5556@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20170102153057.9451-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Taku Izumi <izumi.taku@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-14mm: join struct fault_env and vm_faultJan Kara
Currently we have two different structures for passing fault information around - struct vm_fault and struct fault_env. DAX will need more information in struct vm_fault to handle its faults so the content of that structure would become event closer to fault_env. Furthermore it would need to generate struct fault_env to be able to call some of the generic functions. So at this point I don't think there's much use in keeping these two structures separate. Just embed into struct vm_fault all that is needed to use it for both purposes. Link: http://lkml.kernel.org/r/1479460644-25076-2-git-send-email-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-12mm: make transparent hugepage size publicHugh Dickins
Test programs want to know the size of a transparent hugepage. While it is commonly the same as the size of a hugetlbfs page (shown as Hugepagesize in /proc/meminfo), that is not always so: powerpc implements transparent hugepages in a different way from hugetlbfs pages, so it's coincidence when their sizes are the same; and x86 and others can support more than one hugetlbfs page size. Add /sys/kernel/mm/transparent_hugepage/hpage_pmd_size to show the THP size in bytes - it's the same for Anonymous and Shmem hugepages. Call it hpage_pmd_size (after HPAGE_PMD_SIZE) rather than hpage_size, in case some transparent support for pud and pgd pages is added later. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1612052200290.13021@eggly.anvils Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Greg Thelen <gthelen@google.com> Cc: David Rientjes <rientjes@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-12mm: THP page cache support for ppc64Aneesh Kumar K.V
Add arch specific callback in the generic THP page cache code that will deposit and withdarw preallocated page table. Archs like ppc64 use this preallocated table to store the hash pte slot information. Testing: kernel build of the patch series on tmpfs mounted with option huge=always The related thp stat: thp_fault_alloc 72939 thp_fault_fallback 60547 thp_collapse_alloc 603 thp_collapse_alloc_failed 0 thp_file_alloc 253763 thp_file_mapped 4251 thp_split_page 51518 thp_split_page_failed 1 thp_deferred_split_page 73566 thp_split_pmd 665 thp_zero_page_alloc 3 thp_zero_page_alloc_failed 0 [akpm@linux-foundation.org: remove unneeded parentheses, per Kirill] Link: http://lkml.kernel.org/r/20161113150025.17942-2-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Neuling <mikey@neuling.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-12mm: move vma_is_anonymous check within pmd_move_must_withdrawAneesh Kumar K.V
Independent of whether the vma is for anonymous memory, some arches like ppc64 would like to override pmd_move_must_withdraw(). One option is to encapsulate the vma_is_anonymous() check for general architectures inside pmd_move_must_withdraw() so that is always called and architectures that need unconditional overriding can override this function. ppc64 needs to override the function when the MMU is configured to use hash PTE's. [bsingharora@gmail.com: reworked changelog] Link: http://lkml.kernel.org/r/20161113150025.17942-1-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Neuling <mikey@neuling.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-12mm: add tlb_remove_check_page_size_change to track page size changeAneesh Kumar K.V
With commit e77b0852b551 ("mm/mmu_gather: track page size with mmu gather and force flush if page size change") we added the ability to force a tlb flush when the page size change in a mmu_gather loop. We did that by checking for a page size change every time we added a page to mmu_gather for lazy flush/remove. We can improve that by moving the page size change check early and not doing it every time we add a page. This also helps us to do tlb flush when invalidating a range covering dax mapping. Wrt dax mapping we don't have a backing struct page and hence we don't call tlb_remove_page, which earlier forced the tlb flush on page size change. Moving the page size change check earlier means we will do the same even for dax mapping. We also avoid doing this check on architecture other than powerpc. In a later patch we will remove page size check from tlb_remove_page(). Link: http://lkml.kernel.org/r/20161026084839.27299-5-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-12mm: use the correct page size when removing the pageAneesh Kumar K.V
We are removing a pmd hugepage here. Use the correct page size. Link: http://lkml.kernel.org/r/20161026084839.27299-2-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-12Merge branch 'mm-pat-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull mm/PAT cleanup from Ingo Molnar: "A single cleanup for a generic interface that was originally introduced for PAT" * 'mm-pat-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/pat, mm: Make track_pfn_insert() return void
2016-11-29mremap: move_ptes: check pte dirty after its removalAaron Lu
Linus found there still is a race in mremap after commit 5d1904204c99 ("mremap: fix race between mremap() and page cleanning"). As described by Linus: "the issue is that another thread might make the pte be dirty (in the hardware walker, so no locking of ours will make any difference) *after* we checked whether it was dirty, but *before* we removed it from the page tables" Fix it by moving the check after we removed it from the page table. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-17mremap: fix race between mremap() and page cleanningAaron Lu
Prior to 3.15, there was a race between zap_pte_range() and page_mkclean() where writes to a page could be lost. Dave Hansen discovered by inspection that there is a similar race between move_ptes() and page_mkclean(). We've been able to reproduce the issue by enlarging the race window with a msleep(), but have not been able to hit it without modifying the code. So, we think it's a real issue, but is difficult or impossible to hit in practice. The zap_pte_range() issue is fixed by commit 1cf35d47712d("mm: split 'tlb_flush_mmu()' into tlb flushing and memory freeing parts"). And this patch is to fix the race between page_mkclean() and mremap(). Here is one possible way to hit the race: suppose a process mmapped a file with READ | WRITE and SHARED, it has two threads and they are bound to 2 different CPUs, e.g. CPU1 and CPU2. mmap returned X, then thread 1 did a write to addr X so that CPU1 now has a writable TLB for addr X on it. Thread 2 starts mremaping from addr X to Y while thread 1 cleaned the page and then did another write to the old addr X again. The 2nd write from thread 1 could succeed but the value will get lost. thread 1 thread 2 (bound to CPU1) (bound to CPU2) 1: write 1 to addr X to get a writeable TLB on this CPU 2: mremap starts 3: move_ptes emptied PTE for addr X and setup new PTE for addr Y and then dropped PTL for X and Y 4: page laundering for N by doing fadvise FADV_DONTNEED. When done, pageframe N is deemed clean. 5: *write 2 to addr X 6: tlb flush for addr X 7: munmap (Y, pagesize) to make the page unmapped 8: fadvise with FADV_DONTNEED again to kick the page off the pagecache 9: pread the page from file to verify the value. If 1 is there, it means we have lost the written 2. *the write may or may not cause segmentation fault, it depends on if the TLB is still on the CPU. Please note that this is only one specific way of how the race could occur, it didn't mean that the race could only occur in exact the above config, e.g. more than 2 threads could be involved and fadvise() could be done in another thread, etc. For anonymous pages, they could race between mremap() and page reclaim: THP: a huge PMD is moved by mremap to a new huge PMD, then the new huge PMD gets unmapped/splitted/pagedout before the flush tlb happened for the old huge PMD in move_page_tables() and we could still write data to it. The normal anonymous page has similar situation. To fix this, check for any dirty PTE in move_ptes()/move_huge_pmd() and if any, did the flush before dropping the PTL. If we did the flush for every move_ptes()/move_huge_pmd() call then we do not need to do the flush in move_pages_tables() for the whole range. But if we didn't, we still need to do the whole range flush. Alternatively, we can track which part of the range is flushed in move_ptes()/move_huge_pmd() and which didn't to avoid flushing the whole range in move_page_tables(). But that would require multiple tlb flushes for the different sub-ranges and should be less efficient than the single whole range flush. KBuild test on my Sandybridge desktop doesn't show any noticeable change. v4.9-rc4: real 5m14.048s user 32m19.800s sys 4m50.320s With this commit: real 5m13.888s user 32m19.330s sys 4m51.200s Reported-by: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-09x86/pat, mm: Make track_pfn_insert() return voidBorislav Petkov
It only returns 0 so we can save us the testing of its retval everywhere. Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: mcgrof@suse.com Cc: dri-devel@lists.freedesktop.org Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Airlie <airlied@redhat.com> Cc: dan.j.williams@intel.com Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/20161026174839.rusfxkm3xt4ennhe@pd.tnic Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-10-07mm: vm_page_prot: update with WRITE_ONCE/READ_ONCEAndrea Arcangeli
vma->vm_page_prot is read lockless from the rmap_walk, it may be updated concurrently and this prevents the risk of reading intermediate values. Link: http://lkml.kernel.org/r/1474660305-19222-1-git-send-email-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Jan Vorlicek <janvorli@microsoft.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07thp: reduce usage of huge zero page's atomic counterAaron Lu
The global zero page is used to satisfy an anonymous read fault. If THP(Transparent HugePage) is enabled then the global huge zero page is used. The global huge zero page uses an atomic counter for reference counting and is allocated/freed dynamically according to its counter value. CPU time spent on that counter will greatly increase if there are a lot of processes doing anonymous read faults. This patch proposes a way to reduce the access to the global counter so that the CPU load can be reduced accordingly. To do this, a new flag of the mm_struct is introduced: MMF_USED_HUGE_ZERO_PAGE. With this flag, the process only need to touch the global counter in two cases: 1 The first time it uses the global huge zero page; 2 The time when mm_user of its mm_struct reaches zero. Note that right now, the huge zero page is eligible to be freed as soon as its last use goes away. With this patch, the page will not be eligible to be freed until the exit of the last process from which it was ever used. And with the use of mm_user, the kthread is not eligible to use huge zero page either. Since no kthread is using huge zero page today, there is no difference after applying this patch. But if that is not desired, I can change it to when mm_count reaches zero. Case used for test on Haswell EP: usemem -n 72 --readonly -j 0x200000 100G Which spawns 72 processes and each will mmap 100G anonymous space and then do read only access to that space sequentially with a step of 2MB. CPU cycles from perf report for base commit: 54.03% usemem [kernel.kallsyms] [k] get_huge_zero_page CPU cycles from perf report for this commit: 0.11% usemem [kernel.kallsyms] [k] mm_get_huge_zero_page Performance(throughput) of the workload for base commit: 1784430792 Performance(throughput) of the workload for this commit: 4726928591 164% increase. Runtime of the workload for base commit: 707592 us Runtime of the workload for this commit: 303970 us 50% drop. Link: http://lkml.kernel.org/r/fe51a88f-446a-4622-1363-ad1282d71385@intel.com Signed-off-by: Aaron Lu <aaron.lu@intel.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07thp, dax: add thp_get_unmapped_area for pmd mappingsToshi Kani
When CONFIG_FS_DAX_PMD is set, DAX supports mmap() using pmd page size. This feature relies on both mmap virtual address and FS block (i.e. physical address) to be aligned by the pmd page size. Users can use mkfs options to specify FS to align block allocations. However, aligning mmap address requires code changes to existing applications for providing a pmd-aligned address to mmap(). For instance, fio with "ioengine=mmap" performs I/Os with mmap() [1]. It calls mmap() with a NULL address, which needs to be changed to provide a pmd-aligned address for testing with DAX pmd mappings. Changing all applications that call mmap() with NULL is undesirable. Add thp_get_unmapped_area(), which can be called by filesystem's get_unmapped_area to align an mmap address by the pmd size for a DAX file. It calls the default handler, mm->get_unmapped_area(), to find a range and then aligns it for a DAX file. The patch is based on Matthew Wilcox's change that allows adding support of the pud page size easily. [1]: https://github.com/axboe/fio/blob/master/engines/mmap.c Link: http://lkml.kernel.org/r/1472497881-9323-2-git-send-email-toshi.kani@hpe.com Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jan Kara <jack@suse.cz> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>