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2018-10-07percpu: stop leaking bitmap metadata blocksMike Rapoport
The commit ca460b3c9627 ("percpu: introduce bitmap metadata blocks") introduced bitmap metadata blocks. These metadata blocks are allocated whenever a new chunk is created, but they are never freed. Fix it. Fixes: ca460b3c9627 ("percpu: introduce bitmap metadata blocks") Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: stable@vger.kernel.org Signed-off-by: Dennis Zhou <dennis@kernel.org>
2018-08-22/proc/meminfo: add percpu populated pages countDennis Zhou (Facebook)
Currently, percpu memory only exposes allocation and utilization information via debugfs. This more or less is only really useful for understanding the fragmentation and allocation information at a per-chunk level with a few global counters. This is also gated behind a config. BPF and cgroup, for example, have seen an increase in use causing increased use of percpu memory. Let's make it easier for someone to identify how much memory is being used. This patch adds the "Percpu" stat to meminfo to more easily look up how much percpu memory is in use. This number includes the cost for all allocated backing pages and not just insight at the per a unit, per chunk level. Metadata is excluded. I think excluding metadata is fair because the backing memory scales with the numbere of cpus and can quickly outweigh the metadata. It also makes this calculation light. Link: http://lkml.kernel.org/r/20180807184723.74919-1-dennisszhou@gmail.com Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-02Merge tag 'arch-removal' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic Pul removal of obsolete architecture ports from Arnd Bergmann: "This removes the entire architecture code for blackfin, cris, frv, m32r, metag, mn10300, score, and tile, including the associated device drivers. I have been working with the (former) maintainers for each one to ensure that my interpretation was right and the code is definitely unused in mainline kernels. Many had fond memories of working on the respective ports to start with and getting them included in upstream, but also saw no point in keeping the port alive without any users. In the end, it seems that while the eight architectures are extremely different, they all suffered the same fate: There was one company in charge of an SoC line, a CPU microarchitecture and a software ecosystem, which was more costly than licensing newer off-the-shelf CPU cores from a third party (typically ARM, MIPS, or RISC-V). It seems that all the SoC product lines are still around, but have not used the custom CPU architectures for several years at this point. In contrast, CPU instruction sets that remain popular and have actively maintained kernel ports tend to all be used across multiple licensees. [ See the new nds32 port merged in the previous commit for the next generation of "one company in charge of an SoC line, a CPU microarchitecture and a software ecosystem" - Linus ] The removal came out of a discussion that is now documented at https://lwn.net/Articles/748074/. Unlike the original plans, I'm not marking any ports as deprecated but remove them all at once after I made sure that they are all unused. Some architectures (notably tile, mn10300, and blackfin) are still being shipped in products with old kernels, but those products will never be updated to newer kernel releases. After this series, we still have a few architectures without mainline gcc support: - unicore32 and hexagon both have very outdated gcc releases, but the maintainers promised to work on providing something newer. At least in case of hexagon, this will only be llvm, not gcc. - openrisc, risc-v and nds32 are still in the process of finishing their support or getting it added to mainline gcc in the first place. They all have patched gcc-7.3 ports that work to some degree, but complete upstream support won't happen before gcc-8.1. Csky posted their first kernel patch set last week, their situation will be similar [ Palmer Dabbelt points out that RISC-V support is in mainline gcc since gcc-7, although gcc-7.3.0 is the recommended minimum - Linus ]" This really says it all: 2498 files changed, 95 insertions(+), 467668 deletions(-) * tag 'arch-removal' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: (74 commits) MAINTAINERS: UNICORE32: Change email account staging: iio: remove iio-trig-bfin-timer driver tty: hvc: remove tile driver tty: remove bfin_jtag_comm and hvc_bfin_jtag drivers serial: remove tile uart driver serial: remove m32r_sio driver serial: remove blackfin drivers serial: remove cris/etrax uart drivers usb: Remove Blackfin references in USB support usb: isp1362: remove blackfin arch glue usb: musb: remove blackfin port usb: host: remove tilegx platform glue pwm: remove pwm-bfin driver i2c: remove bfin-twi driver spi: remove blackfin related host drivers watchdog: remove bfin_wdt driver can: remove bfin_can driver mmc: remove bfin_sdh driver input: misc: remove blackfin rotary driver input: keyboard: remove bf54x driver ...
2018-03-26treewide: simplify Kconfig dependencies for removed archsArnd Bergmann
A lot of Kconfig symbols have architecture specific dependencies. In those cases that depend on architectures we have already removed, they can be omitted. Acked-by: Kalle Valo <kvalo@codeaurora.org> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2018-03-19mm: Allow to kill tasks doing pcpu_alloc() and waiting for pcpu_balance_workfn()Kirill Tkhai
In case of memory deficit and low percpu memory pages, pcpu_balance_workfn() takes pcpu_alloc_mutex for a long time (as it makes memory allocations itself and waits for memory reclaim). If tasks doing pcpu_alloc() are choosen by OOM killer, they can't exit, because they are waiting for the mutex. The patch makes pcpu_alloc() to care about killing signal and use mutex_lock_killable(), when it's allowed by GFP flags. This guarantees, a task does not miss SIGKILL from OOM killer. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2018-03-19percpu: include linux/sched.h for cond_resched()Tejun Heo
microblaze build broke due to missing declaration of the cond_resched() invocation added recently. Let's include linux/sched.h explicitly. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: kbuild test robot <fengguang.wu@intel.com>
2018-02-23percpu: add a schedule point in pcpu_balance_workfn()Eric Dumazet
When a large BPF percpu map is destroyed, I have seen pcpu_balance_workfn() holding cpu for hundreds of milliseconds. On KASAN config and 112 hyperthreads, average time to destroy a chunk is ~4 ms. [ 2489.841376] destroy chunk 1 in 4148689 ns ... [ 2490.093428] destroy chunk 32 in 4072718 ns Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2018-02-18percpu: allow select gfp to be passed to underlying allocatorsDennis Zhou
The prior patch added support for passing gfp flags through to the underlying allocators. This patch allows users to pass along gfp flags (currently only __GFP_NORETRY and __GFP_NOWARN) to the underlying allocators. This should allow users to decide if they are ok with failing allocations recovering in a more graceful way. Additionally, gfp passing was done as additional flags in the previous patch. Instead, change this to caller passed semantics. GFP_KERNEL is also removed as the default flag. It continues to be used for internally caused underlying percpu allocations. V2: Removed gfp_percpu_mask in favor of doing it inline. Removed GFP_KERNEL as a default flag for __alloc_percpu_gfp. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2018-02-18percpu: add __GFP_NORETRY semantics to the percpu balancing pathDennis Zhou
Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] https://lkml.org/lkml/2018/2/12/551 Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2018-02-18percpu: match chunk allocator declarations with definitionsDennis Zhou
At some point the function declaration parameters got out of sync with the function definitions in percpu-vm.c and percpu-km.c. This patch makes them match again. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-11-27percpu: hack to let the CRIS architecture to boot until they clean upNicolas Pitre
Commit 438a506180 ("percpu: don't forget to free the temporary struct pcpu_alloc_info") uncovered a problem on the CRIS architecture where the bootmem allocator is initialized with virtual addresses. Given it has: #define __va(x) ((void *)((unsigned long)(x) | 0x80000000)) then things just work out because the end result is the same whether you give this a physical or a virtual address. Untill you call memblock_free_early(__pa(address)) that is, because values from __pa() don't match with the virtual addresses stuffed in the bootmem allocator anymore. Avoid freeing the temporary pcpu_alloc_info memory on that architecture until they fix things up to let the kernel boot like it did before. Signed-off-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: 438a506180 ("percpu: don't forget to free the temporary struct pcpu_alloc_info")
2017-11-15Merge branch 'for-4.15' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu Pull percpu update from Tejun Heo: "Another minor pull request. It only contains one commit which can reclaim a bit of memory wasted during boot on UP" * 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: percpu: don't forget to free the temporary struct pcpu_alloc_info
2017-10-19mm, percpu: add support for __GFP_NOWARN flagDaniel Borkmann
Add an option for pcpu_alloc() to support __GFP_NOWARN flag. Currently, we always throw a warning when size or alignment is unsupported (and also dump stack on failed allocation requests). The warning itself is harmless since we return NULL anyway for any failed request, which callers are required to handle anyway. However, it becomes harmful when panic_on_warn is set. The rationale for the WARN() in pcpu_alloc() is that it can be tracked when larger than supported allocation requests are made such that allocations limits can be tweaked if warranted. This makes sense for in-kernel users, however, there are users of pcpu allocator where allocation size is derived from user space requests, e.g. when creating BPF maps. In these cases, the requests should fail gracefully without throwing a splat. The current work-around was to check allocation size against the upper limit of PCPU_MIN_UNIT_SIZE from call-sites for bailing out prior to a call to pcpu_alloc() in order to avoid throwing the WARN(). This is bad in multiple ways since PCPU_MIN_UNIT_SIZE is an implementation detail, and having the checks on call-sites only complicates the code for no good reason. Thus, lets fix it generically by supporting the __GFP_NOWARN flag that users can then use with calling the __alloc_percpu_gfp() helper instead. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-10-04percpu: don't forget to free the temporary struct pcpu_alloc_infoNicolas Pitre
Unlike the SMP case, the !SMP case does not free the memory for struct pcpu_alloc_info allocated in setup_per_cpu_areas(). And to give it a chance of being reused by the page allocator later, align it to a page boundary just like its size. Signed-off-by: Nicolas Pitre <nico@linaro.org> Acked-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-09-28percpu: fix iteration to prevent skipping over blockDennis Zhou
The iterator functions pcpu_next_md_free_region and pcpu_next_fit_region use the block offset to determine if they have checked the area in the prior iteration. However, this causes an issue when the block offset is greater than subsequent block contig hints. If within the iterator it moves to check subsequent blocks, it may fail in the second predicate due to the block offset not being cleared. Thus, this causes the allocator to skip over blocks leading to false failures when allocating from the reserved chunk. While this happens in the general case as well, it will only fail if it cannot allocate a new chunk. This patch resets the block offset to 0 to pass the second predicate when checking subseqent blocks within the iterator function. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reported-and-tested-by: Luis Henriques <lhenriques@suse.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: update header to contain bitmap allocator explanation.Dennis Zhou (Facebook)
The other patches contain a lot of information, so adding this information in a separate patch. It adds my copyright and a brief explanation of how the bitmap allocator works. There is a minor typo as well in the prior explanation so that is fixed. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: update pcpu_find_block_fit to use an iteratorDennis Zhou (Facebook)
The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: use metadata blocks to update the chunk contig hintDennis Zhou (Facebook)
The largest free region will either be a block level contig hint or an aggregate over the left_free and right_free areas of blocks. This is a much smaller set of free areas that need to be checked than a full traverse. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: update free path to take advantage of contig hintsDennis Zhou (Facebook)
The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: update alloc path to only scan if contig hints are brokenDennis Zhou (Facebook)
Metadata is kept per block to keep track of where the contig hints are. Scanning can be avoided when the contig hints are not broken. In that case, left and right contigs have to be managed manually. This patch changes the allocation path hint updating to only scan when contig hints are broken. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: keep track of the best offset for contig hintsDennis Zhou (Facebook)
This patch makes the contig hint starting offset optimization from the previous patch as honest as it can be. For both chunk and block starting offsets, make sure it keeps the starting offset with the best alignment. The block skip optimization is added in a later patch when the pcpu_find_block_fit iterator is swapped in. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: skip chunks if the alloc does not fit in the contig hintDennis Zhou (Facebook)
This patch adds chunk->contig_bits_start to keep track of the contig hint's offset and the check to skip the chunk if it does not fit. If the chunk's contig hint starting offset cannot satisfy an allocation, the allocator assumes there is enough memory pressure in this chunk to either use a different chunk or create a new one. This accepts a less tight packing for a smoother latency curve. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: add first_bit to keep track of the first free in the bitmapDennis Zhou (Facebook)
This patch adds first_bit to keep track of the first free bit in the bitmap. This hint helps prevent scanning of fully allocated blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: introduce bitmap metadata blocksDennis Zhou (Facebook)
This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: replace area map allocator with bitmapDennis Zhou (Facebook)
The percpu memory allocator is experiencing scalability issues when allocating and freeing large numbers of counters as in BPF. Additionally, there is a corner case where iteration is triggered over all chunks if the contig_hint is the right size, but wrong alignment. This patch replaces the area map allocator with a basic bitmap allocator implementation. Each subsequent patch will introduce new features and replace full scanning functions with faster non-scanning options when possible. Implementation: This patchset removes the area map allocator in favor of a bitmap allocator backed by metadata blocks. The primary goal is to provide consistency in performance and memory footprint with a focus on small allocations (< 64 bytes). The bitmap removes the heavy memmove from the freeing critical path and provides a consistent memory footprint. The metadata blocks provide a bound on the amount of scanning required by maintaining a set of hints. In an effort to make freeing fast, the metadata is updated on the free path if the new free area makes a page free, a block free, or spans across blocks. This causes the chunk's contig hint to potentially be smaller than what it could allocate by up to the smaller of a page or a block. If the chunk's contig hint is contained within a block, a check occurs and the hint is kept accurate. Metadata is always kept accurate on allocation, so there will not be a situation where a chunk has a later contig hint than available. Evaluation: I have primarily done testing against a simple workload of allocation of 1 million objects (2^20) of varying size. Deallocation was done by in order, alternating, and in reverse. These numbers were collected after rebasing ontop of a80099a152. I present the worst-case numbers here: Area Map Allocator: Object Size | Alloc Time (ms) | Free Time (ms) ---------------------------------------------- 4B | 310 | 4770 16B | 557 | 1325 64B | 436 | 273 256B | 776 | 131 1024B | 3280 | 122 Bitmap Allocator: Object Size | Alloc Time (ms) | Free Time (ms) ---------------------------------------------- 4B | 490 | 70 16B | 515 | 75 64B | 610 | 80 256B | 950 | 100 1024B | 3520 | 200 This data demonstrates the inability for the area map allocator to handle less than ideal situations. In the best case of reverse deallocation, the area map allocator was able to perform within range of the bitmap allocator. In the worst case situation, freeing took nearly 5 seconds for 1 million 4-byte objects. The bitmap allocator dramatically improves the consistency of the free path. The small allocations performed nearly identical regardless of the freeing pattern. While it does add to the allocation latency, the allocation scenario here is optimal for the area map allocator. The area map allocator runs into trouble when it is allocating in chunks where the latter half is full. It is difficult to replicate this, so I present a variant where the pages are second half filled. Freeing was done sequentially. Below are the numbers for this scenario: Area Map Allocator: Object Size | Alloc Time (ms) | Free Time (ms) ---------------------------------------------- 4B | 4118 | 4892 16B | 1651 | 1163 64B | 598 | 285 256B | 771 | 158 1024B | 3034 | 160 Bitmap Allocator: Object Size | Alloc Time (ms) | Free Time (ms) ---------------------------------------------- 4B | 481 | 67 16B | 506 | 69 64B | 636 | 75 256B | 892 | 90 1024B | 3262 | 147 The data shows a parabolic curve of performance for the area map allocator. This is due to the memmove operation being the dominant cost with the lower object sizes as more objects are packed in a chunk and at higher object sizes, the traversal of the chunk slots is the dominating cost. The bitmap allocator suffers this problem as well. The above data shows the inability to scale for the allocation path with the area map allocator and that the bitmap allocator demonstrates consistent performance in general. The second problem of additional scanning can result in the area map allocator completing in 52 minutes when trying to allocate 1 million 4-byte objects with 8-byte alignment. The same workload takes approximately 16 seconds to complete for the bitmap allocator. V2: Fixed a bug in pcpu_alloc_first_chunk end_offset was setting the bitmap using bytes instead of bits. Added a comment to pcpu_cnt_pop_pages to explain bitmap_weight. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: generalize bitmap (un)populated iteratorsDennis Zhou (Facebook)
The area map allocator only used a bitmap for the backing page state. The new bitmap allocator will use bitmaps to manage the allocation region in addition to this. This patch generalizes the bitmap iterators so they can be reused with the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: increase minimum percpu allocation size and align first regionsDennis Zhou (Facebook)
This patch increases the minimum allocation size of percpu memory to 4-bytes. This change will help minimize the metadata overhead associated with the bitmap allocator. The assumption is that most allocations will be of objects or structs greater than 2 bytes with integers or longs being used rather than shorts. The first chunk regions are now aligned with the minimum allocation size. The reserved region is expected to be set as a multiple of the minimum allocation size. The static region is aligned up and the delta is removed from the dynamic size. This works because the dynamic size is increased to be page aligned. If the static size is not minimum allocation size aligned, then there must be a gap that is added to the dynamic size. The dynamic size will never be smaller than the set value. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: introduce nr_empty_pop_pages to help empty page accountingDennis Zhou (Facebook)
pcpu_nr_empty_pop_pages is used to ensure there are a handful of free pages around to serve atomic allocations. A new field, nr_empty_pop_pages, is added to the pcpu_chunk struct to keep track of the number of empty pages. This field is needed as the number of empty populated pages is globally tracked and deltas are used to update in the bitmap allocator. Pages that contain a hidden area are not considered to be empty. This new field is exposed in percpu_stats. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: change the number of pages marked in the first_chunk pop bitmapDennis Zhou (Facebook)
The populated bitmap represents the state of the pages the chunk serves. Prior, the bitmap was marked completely used as the first chunk was allocated and immutable. This is misleading because the first chunk may not be completely filled. Additionally, with moving the base_addr up in the previous patch, the population check no longer corresponds to what was being checked. This patch modifies the population map to be only the number of pages the region serves and to make what it was checking correspond correctly again. The change is to remove any misunderstanding between the size of the populated bitmap and the actual size of it. The work function page iterators now use nr_pages for the check rather than pcpu_unit_pages because nr_populated is now chunk specific. Without this, the work function would try to populate the remainder of these chunks despite it not serving any more than nr_pages when nr_pages is set less than pcpu_unit_pages. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: combine percpu address checksDennis Zhou (Facebook)
The percpu address checks for the reserved and dynamic region chunks are now specific to each region. The address checking logic can be combined taking advantage of the global references to the dynamic and static region chunks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: modify base_addr to be region specificDennis Zhou (Facebook)
Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: setup_first_chunk rename schunk/dchunk to chunkDennis Zhou (Facebook)
There is no need to have the static chunk and dynamic chunk be named separately as the allocations are sequential. This preemptively solves the misnomer problem with the base_addrs being moved up in the following patch. It also removes a ternary operation deciding the first chunk. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: end chunk area maps page aligned for the populated bitmapDennis Zhou (Facebook)
The area map allocator manages the first chunk area by hiding all but the region it is responsible for serving in the area map. To align this with the populated page bitmap, end_offset is introduced to keep track of the delta to end page aligned. The area map is appended with the page aligned end when necessary to be in line with how the bitmap allocator requires the ending to be aligned with the LCM of PAGE_SIZE and the size of each bitmap block. percpu_stats is updated to ignore this region when present. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: unify allocation of schunk and dchunkDennis Zhou (Facebook)
Create a common allocator for first chunk initialization, pcpu_alloc_first_chunk. Comments for this function will be added in a later patch once the bitmap allocator is added. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: setup_first_chunk remove dyn_size and consolidate logicDennis Zhou (Facebook)
There is logic for setting variables in the static chunk init code that could be consolidated with the dynamic chunk init code. This combines this logic to setup for combining the allocation paths. reserved_size is used as the conditional as a dynamic region will always exist. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: remove has_reserved from pcpu_chunkDennis Zhou (Facebook)
Prior this variable was used to manage statistics when the first chunk had a reserved region. The previous patch introduced start_offset to keep track of the offset by value rather than boolean. Therefore, has_reserved can be removed. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: introduce start_offset to pcpu_chunkDennis Zhou (Facebook)
The reserved chunk arithmetic uses a global variable pcpu_reserved_chunk_limit that is set in the first chunk init code to hide a portion of the area map. The bitmap allocator to come will eventually move the base_addr up and require both the reserved chunk and static chunk to maintain this offset. pcpu_reserved_chunk_limit is removed and start_offset is added. The first chunk that is circulated and is pcpu_first_chunk serves the dynamic region, the region following the reserved region. The reserved chunk address check will temporarily use the first chunk to identify its address range. A following patch will increase the base_addr and remove this. If there is no reserved chunk, this will check the static region and return false because those values should never be passed into the allocator. Lastly, when linking in the first chunk, make sure to count the right free region for the number of empty populated pages. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: setup_first_chunk enforce dynamic region must existDennis Zhou (Facebook)
The first chunk is handled as a special case as it is composed of the static, reserved, and dynamic regions. The code handles each case individually. The next several patches will merge these code paths and lay the foundation for the bitmap allocator. This patch modifies logic to enforce that a dynamic region exists and changes the area map to account for that. This brings the logic closer to the dynamic chunk's init logic. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-17percpu: update the header comment and pcpu_build_alloc_info commentsDennis Zhou (Facebook)
The header comment for percpu memory is a little hard to parse and is not super clear about how the first chunk is managed. This adds a little more clarity to the situation. There is also quite a bit of tricky logic in the pcpu_build_alloc_info. This adds a restructure of a comment to add a little more information. Unfortunately, you will still have to piece together a handful of other comments too, but should help direct you to the meaningful comments. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-17percpu: expose pcpu_nr_empty_pop_pages in pcpu_statsDennis Zhou (Facebook)
Percpu memory holds a minimum threshold of pages that are populated in order to serve atomic percpu memory requests. This change makes it easier to verify that there are a minimum number of populated pages lying around. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-06-21percpu: resolve err may not be initialized in pcpu_allocDennis Zhou
From 4a42ecc735cff0015cc73c3d87edede631f4b885 Mon Sep 17 00:00:00 2001 From: Dennis Zhou <dennisz@fb.com> Date: Wed, 21 Jun 2017 08:07:15 -0700 Add error message to out of space failure for atomic allocations in percpu allocation path to fix -Wmaybe-uninitialized. Signed-off-by: Dennis Zhou <dennisz@fb.com> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-06-20percpu: add tracepoint support for percpu memoryDennis Zhou
Add support for tracepoints to the following events: chunk allocation, chunk free, area allocation, area free, and area allocation failure. This should let us replay percpu memory requests and evaluate corresponding decisions. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-06-20percpu: expose statistics about percpu memory via debugfsDennis Zhou
There is limited visibility into the use of percpu memory leaving us unable to reason about correctness of parameters and overall use of percpu memory. These counters and statistics aim to help understand basic statistics about percpu memory such as number of allocations over the lifetime, allocation sizes, and fragmentation. New Config: PERCPU_STATS Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-06-20percpu: migrate percpu data structures to internal headerDennis Zhou
Migrates pcpu_chunk definition and a few percpu static variables to an internal header file from mm/percpu.c. These will be used with debugfs to expose statistics about percpu memory improving visibility regarding allocations and fragmentation. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-06-20percpu: add missing lockdep_assert_held to func pcpu_free_areaDennis Zhou
Add a missing lockdep_assert_held for pcpu_lock to improve consistency and safety throughout mm/percpu.c. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-05-10mark most percpu globals as __ro_after_initDaniel Micay
Moving pcpu_base_addr to this section comes from PaX where it's part of KERNEXEC. This extends it to the rest of the globals only written by the init code. Signed-off-by: Daniel Micay <danielmicay@gmail.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-04-04Merge branch 'sched/core' into locking/coreThomas Gleixner
Required for the rtmutex/sched_deadline patches which depend on both branches
2017-03-26lockdep: Fix per-cpu static objectsPeter Zijlstra
Since commit 383776fa7527 ("locking/lockdep: Handle statically initialized PER_CPU locks properly") we try to collapse per-cpu locks into a single class by giving them all the same key. For this key we choose the canonical address of the per-cpu object, which would be the offset into the per-cpu area. This has two problems: - there is a case where we run !0 lock->key through static_obj() and expect this to pass; it doesn't for canonical pointers. - 0 is a valid canonical address. Cure both issues by redefining the canonical address as the address of the per-cpu variable on the boot CPU. Since I didn't want to rely on CPU0 being the boot-cpu, or even existing at all, track the boot CPU in a variable. Fixes: 383776fa7527 ("locking/lockdep: Handle statically initialized PER_CPU locks properly") Reported-by: kernel test robot <fengguang.wu@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Borislav Petkov <bp@suse.de> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: linux-mm@kvack.org Cc: wfg@linux.intel.com Cc: kernel test robot <fengguang.wu@intel.com> Cc: LKP <lkp@01.org> Link: http://lkml.kernel.org/r/20170320114108.kbvcsuepem45j5cr@hirez.programming.kicks-ass.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-03-16locking/lockdep: Handle statically initialized PER_CPU locks properlyThomas Gleixner
If a PER_CPU struct which contains a spin_lock is statically initialized via: DEFINE_PER_CPU(struct foo, bla) = { .lock = __SPIN_LOCK_UNLOCKED(bla.lock) }; then lockdep assigns a seperate key to each lock because the logic for assigning a key to statically initialized locks is to use the address as the key. With per CPU locks the address is obvioulsy different on each CPU. That's wrong, because all locks should have the same key. To solve this the following modifications are required: 1) Extend the is_kernel/module_percpu_addr() functions to hand back the canonical address of the per CPU address, i.e. the per CPU address minus the per CPU offset. 2) Check the lock address with these functions and if the per CPU check matches use the returned canonical address as the lock key, so all per CPU locks have the same key. 3) Move the static_obj(key) check into look_up_lock_class() so this check can be avoided for statically initialized per CPU locks. That's required because the canonical address fails the static_obj(key) check for obvious reasons. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ Merged Dan's fixups for !MODULES and !SMP into this patch. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Murphy <dmurphy@ti.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170227143736.pectaimkjkan5kow@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-06percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pagesTahsin Erdogan
Update to pcpu_nr_empty_pop_pages in pcpu_alloc() is currently done without holding pcpu_lock. This can lead to bad updates to the variable. Add missing lock calls. Fixes: b539b87fed37 ("percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated") Signed-off-by: Tahsin Erdogan <tahsin@google.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org # v3.18+