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2019-08-14arm64: memory: Implement __tag_set() as common functionWill Deacon
There's no need for __tag_set() to be a complicated macro when CONFIG_KASAN_SW_TAGS=y and a simple static inline otherwise. Rewrite the thing as a common static inline function. Tested-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Steve Capper <steve.capper@arm.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-14arm64: memory: Simplify _VA_START and _PAGE_OFFSET definitionsWill Deacon
Rather than subtracting from -1 and then adding 1, we can simply subtract from 0. Tested-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Steve Capper <steve.capper@arm.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-14arm64: memory: Simplify virt_to_page() implementationWill Deacon
Build virt_to_page() on top of virt_to_pfn() so we can avoid the need for explicit shifting. Tested-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Steve Capper <steve.capper@arm.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-14arm64: memory: Rewrite default page_to_virt()/virt_to_page()Will Deacon
The default implementations of page_to_virt() and virt_to_page() are fairly confusing to read and the former evaluates its 'page' parameter twice in the macro Rewrite them so that the computation is expressed as 'base + index' in both cases and the parameter is always evaluated exactly once. Tested-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Steve Capper <steve.capper@arm.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-14arm64: memory: Ensure address tag is masked in conversion macrosWill Deacon
When converting a linear virtual address to a physical address, pfn or struct page *, we must make sure that the tag bits are masked before the calculation otherwise we end up with corrupt pointers when running with CONFIG_KASAN_SW_TAGS=y: | Unable to handle kernel paging request at virtual address 0037fe0007580d08 | [0037fe0007580d08] address between user and kernel address ranges Mask out the tag in __virt_to_phys_nodebug() and virt_to_page(). Reported-by: Qian Cai <cai@lca.pw> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Steve Capper <steve.capper@arm.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Fixes: 9cb1c5ddd2c4 ("arm64: mm: Remove bit-masking optimisations for PAGE_OFFSET and VMEMMAP_START") Signed-off-by: Will Deacon <will@kernel.org>
2019-08-14arm64: memory: Fix virt_addr_valid() using __is_lm_address()Will Deacon
virt_addr_valid() is intended to test whether or not the passed address is a valid linear map address. Unfortunately, it relies on _virt_addr_is_linear() which is broken because it assumes the linear map is at the top of the address space, which it no longer is. Reimplement virt_addr_valid() using __is_lm_address() and remove _virt_addr_is_linear() entirely. At the same time, ensure we evaluate the macro parameter only once and move it within the __ASSEMBLY__ block. Reported-by: Qian Cai <cai@lca.pw> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Steve Capper <steve.capper@arm.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Fixes: 14c127c957c1 ("arm64: mm: Flip kernel VA space") Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: mm: Simplify definition of virt_addr_valid()Will Deacon
_virt_addr_valid() is defined as the same value in two places and rolls its own version of virt_to_pfn() in both cases. Consolidate these definitions by inlining a simplified version directly into virt_addr_valid(). Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09docs: arm64: Add layout and 52-bit info to memory documentSteve Capper
As the kernel no longer prints out the memory layout on boot, this patch adds this information back to the memory document. Also, as the 52-bit support introduces some subtle changes to the arm64 memory, the rationale behind these changes are also added to the memory document. Signed-off-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: mm: Remove vabits_userSteve Capper
Previous patches have enabled 52-bit kernel + user VAs and there is no longer any scenario where user VA != kernel VA size. This patch removes the, now redundant, vabits_user variable and replaces usage with vabits_actual where appropriate. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Steve Capper <steve.capper@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: mm: Introduce 52-bit Kernel VAsSteve Capper
Most of the machinery is now in place to enable 52-bit kernel VAs that are detectable at boot time. This patch adds a Kconfig option for 52-bit user and kernel addresses and plumbs in the requisite CONFIG_ macros as well as sets TCR.T1SZ, physvirt_offset and vmemmap at early boot. To simplify things this patch also removes the 52-bit user/48-bit kernel kconfig option. Signed-off-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: mm: Modify calculation of VMEMMAP_SIZESteve Capper
In a later patch we will need to have a slightly larger VMEMMAP region to accommodate boot time selection between 48/52-bit kernel VAs. This patch modifies the formula for computing VMEMMAP_SIZE to depend explicitly on the PAGE_OFFSET and start of kernel addressable memory. (This allows for a slightly larger direct linear map in future). Signed-off-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: mm: Separate out vmemmapSteve Capper
vmemmap is a preprocessor definition that depends on a variable, memstart_addr. In a later patch we will need to expand the size of the VMEMMAP region and optionally modify vmemmap depending upon whether or not hardware support is available for 52-bit virtual addresses. This patch changes vmemmap to be a variable. As the old definition depended on a variable load, this should not affect performance noticeably. Signed-off-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: mm: Logic to make offset_ttbr1 conditionalSteve Capper
When running with a 52-bit userspace VA and a 48-bit kernel VA we offset ttbr1_el1 to allow the kernel pagetables with a 52-bit PTRS_PER_PGD to be used for both userspace and kernel. Moving on to a 52-bit kernel VA we no longer require this offset to ttbr1_el1 should we be running on a system with HW support for 52-bit VAs. This patch introduces conditional logic to offset_ttbr1 to query SYS_ID_AA64MMFR2_EL1 whenever 52-bit VAs are selected. If there is HW support for 52-bit VAs then the ttbr1 offset is skipped. We choose to read a system register rather than vabits_actual because offset_ttbr1 can be called in places where the kernel data is not actually mapped. Calls to offset_ttbr1 appear to be made from rarely called code paths so this extra logic is not expected to adversely affect performance. Signed-off-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: mm: Introduce vabits_actualSteve Capper
In order to support 52-bit kernel addresses detectable at boot time, one needs to know the actual VA_BITS detected. A new variable vabits_actual is introduced in this commit and employed for the KVM hypervisor layout, KASAN, fault handling and phys-to/from-virt translation where there would normally be compile time constants. In order to maintain performance in phys_to_virt, another variable physvirt_offset is introduced. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Steve Capper <steve.capper@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: mm: Introduce VA_BITS_MINSteve Capper
In order to support 52-bit kernel addresses detectable at boot time, the kernel needs to know the most conservative VA_BITS possible should it need to fall back to this quantity due to lack of hardware support. A new compile time constant VA_BITS_MIN is introduced in this patch and it is employed in the KASAN end address, KASLR, and EFI stub. For Arm, if 52-bit VA support is unavailable the fallback is to 48-bits. In other words: VA_BITS_MIN = min (48, VA_BITS) Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Steve Capper <steve.capper@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: dump: De-constify VA_START and KASAN_SHADOW_STARTSteve Capper
The kernel page table dumper assumes that the placement of VA regions is constant and determined at compile time. As we are about to introduce variable VA logic, we need to be able to determine certain regions at boot time. Specifically the VA_START and KASAN_SHADOW_START will depend on whether or not the system is booted with 52-bit kernel VAs. This patch adds logic to the kernel page table dumper s.t. these regions can be computed at boot time. Signed-off-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: kasan: Switch to using KASAN_SHADOW_OFFSETSteve Capper
KASAN_SHADOW_OFFSET is a constant that is supplied to gcc as a command line argument and affects the codegen of the inline address sanetiser. Essentially, for an example memory access: *ptr1 = val; The compiler will insert logic similar to the below: shadowValue = *(ptr1 >> KASAN_SHADOW_SCALE_SHIFT + KASAN_SHADOW_OFFSET) if (somethingWrong(shadowValue)) flagAnError(); This code sequence is inserted into many places, thus KASAN_SHADOW_OFFSET is essentially baked into many places in the kernel text. If we want to run a single kernel binary with multiple address spaces, then we need to do this with KASAN_SHADOW_OFFSET fixed. Thankfully, due to the way the KASAN_SHADOW_OFFSET is used to provide shadow addresses we know that the end of the shadow region is constant w.r.t. VA space size: KASAN_SHADOW_END = ~0 >> KASAN_SHADOW_SCALE_SHIFT + KASAN_SHADOW_OFFSET This means that if we increase the size of the VA space, the start of the KASAN region expands into lower addresses whilst the end of the KASAN region is fixed. Currently the arm64 code computes KASAN_SHADOW_OFFSET at build time via build scripts with the VA size used as a parameter. (There are build time checks in the C code too to ensure that expected values are being derived). It is sufficient, and indeed is a simplification, to remove the build scripts (and build time checks) entirely and instead provide KASAN_SHADOW_OFFSET values. This patch removes the logic to compute the KASAN_SHADOW_OFFSET in the arm64 Makefile, and instead we adopt the approach used by x86 to supply offset values in kConfig. To help debug/develop future VA space changes, the Makefile logic has been preserved in a script file in the arm64 Documentation folder. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Steve Capper <steve.capper@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: mm: Flip kernel VA spaceSteve Capper
In order to allow for a KASAN shadow that changes size at boot time, one must fix the KASAN_SHADOW_END for both 48 & 52-bit VAs and "grow" the start address. Also, it is highly desirable to maintain the same function addresses in the kernel .text between VA sizes. Both of these requirements necessitate us to flip the kernel address space halves s.t. the direct linear map occupies the lower addresses. This patch puts the direct linear map in the lower addresses of the kernel VA range and everything else in the higher ranges. We need to adjust: *) KASAN shadow region placement logic, *) KASAN_SHADOW_OFFSET computation logic, *) virt_to_phys, phys_to_virt checks, *) page table dumper. These are all small changes, that need to take place atomically, so they are bundled into this commit. As part of the re-arrangement, a guard region of 2MB (to preserve alignment for fixed map) is added after the vmemmap. Otherwise the vmemmap could intersect with IS_ERR pointers. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Steve Capper <steve.capper@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-09arm64: mm: Remove bit-masking optimisations for PAGE_OFFSET and VMEMMAP_STARTSteve Capper
Currently there are assumptions about the alignment of VMEMMAP_START and PAGE_OFFSET that won't be valid after this series is applied. These assumptions are in the form of bitwise operators being used instead of addition and subtraction when calculating addresses. This patch replaces these bitwise operators with addition/subtraction. Signed-off-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2019-08-04Linux 5.3-rc3Linus Torvalds
2019-08-04Merge tag 'tpmdd-next-20190805' of git://git.infradead.org/users/jjs/linux-tpmddLinus Torvalds
Pull tpm fixes from Jarkko Sakkinen: "Two bug fixes that did not make into my first pull request" * tag 'tpmdd-next-20190805' of git://git.infradead.org/users/jjs/linux-tpmdd: tpm: tpm_ibm_vtpm: Fix unallocated banks tpm: Fix null pointer dereference on chip register error path
2019-08-04Merge tag 'mtd/fixes-for-5.3-rc3' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux Pull MTD fixes from Miquel Raynal: "NAND: - Fix Micron driver as some chips enable internal ECC correction during their discovery while they advertize they do not have any. Hyperbus: - Restrict the build to only ARM64 SoCs (and compile testing) which is what should have been done since the beginning. - Fix Kconfig issue by selection something instead of implying it" * tag 'mtd/fixes-for-5.3-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux: mtd: hyperbus: Add hardware dependency to AM654 driver mtd: hyperbus: Kconfig: Fix HBMC_AM654 dependencies mtd: rawnand: micron: handle on-die "ECC-off" devices correctly
2019-08-05tpm: tpm_ibm_vtpm: Fix unallocated banksNayna Jain
The nr_allocated_banks and allocated banks are initialized as part of tpm_chip_register. Currently, this is done as part of auto startup function. However, some drivers, like the ibm vtpm driver, do not run auto startup during initialization. This results in uninitialized memory issue and causes a kernel panic during boot. This patch moves the pcr allocation outside the auto startup function into tpm_chip_register. This ensures that allocated banks are initialized in any case. Fixes: 879b589210a9 ("tpm: retrieve digest size of unknown algorithms with PCR read") Reported-by: Michal Suchanek <msuchanek@suse.de> Signed-off-by: Nayna Jain <nayna@linux.ibm.com> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com> Tested-by: Michal Suchánek <msuchanek@suse.de> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2019-08-05tpm: Fix null pointer dereference on chip register error pathMilan Broz
If clk_enable is not defined and chip initialization is canceled code hits null dereference. Easily reproducible with vTPM init fail: swtpm chardev --tpmstate dir=nonexistent_dir --tpm2 --vtpm-proxy BUG: kernel NULL pointer dereference, address: 00000000 ... Call Trace: tpm_chip_start+0x9d/0xa0 [tpm] tpm_chip_register+0x10/0x1a0 [tpm] vtpm_proxy_work+0x11/0x30 [tpm_vtpm_proxy] process_one_work+0x214/0x5a0 worker_thread+0x134/0x3e0 ? process_one_work+0x5a0/0x5a0 kthread+0xd4/0x100 ? process_one_work+0x5a0/0x5a0 ? kthread_park+0x90/0x90 ret_from_fork+0x19/0x24 Fixes: 719b7d81f204 ("tpm: introduce tpm_chip_start() and tpm_chip_stop()") Cc: stable@vger.kernel.org # v5.1+ Signed-off-by: Milan Broz <gmazyland@gmail.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2019-08-04Merge tag 'powerpc-5.3-3' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux Pull powerpc fixes from Michael Ellerman: "Some more powerpc fixes for 5.3: - Wire up the new clone3 syscall. - A fix for the PAPR SCM nvdimm driver, to fix a crash when firmware gives us a device that's attached to a non-online NUMA node. - A fix for a boot failure on 32-bit with KASAN enabled. - Three fixes for implicit fall through warnings, some of which are errors for us due to -Werror. Thanks to: Aneesh Kumar K.V, Christophe Leroy, Kees Cook, Santosh Sivaraj, Stephen Rothwell" * tag 'powerpc-5.3-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/kasan: fix early boot failure on PPC32 drivers/macintosh/smu.c: Mark expected switch fall-through powerpc/spe: Mark expected switch fall-throughs powerpc/nvdimm: Pick nearby online node if the device node is not online powerpc/kvm: Fall through switch case explicitly powerpc: Wire up clone3 syscall
2019-08-04MAINTAINERS: Add Geert as Renesas SoC Co-MaintainerGeert Uytterhoeven
At the end of the v5.3 upstream kernel development cycle, Simon will be stepping down from his role as Renesas SoC maintainer. Starting with the v5.4 development cycle, Geert is taking over this role. Add Geert as a co-maintainer, and add his git repository and branch. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se> Acked-by: Simon Horman <horms+renesas@verge.net.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-04Merge tag 'kbuild-fixes-v5.3-2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild fixes from Masahiro Yamada: - detect missing missing "WITH Linux-syscall-note" for uapi headers - fix needless rebuild when using Clang - fix false-positive cc-option in Kconfig when using Clang - avoid including corrupted .*.cmd files in the modpost stage - fix warning of 'make vmlinux' - fix {m,n,x,g}config to not generate the broken .config on the second save operation. - some trivial Makefile fixes * tag 'kbuild-fixes-v5.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kconfig: Clear "written" flag to avoid data loss kbuild: Check for unknown options with cc-option usage in Kconfig and clang lib/raid6: fix unnecessary rebuild of vpermxor*.c kbuild: modpost: do not parse unnecessary rules for vmlinux modpost kbuild: modpost: remove unnecessary dependency for __modpost kbuild: modpost: handle KBUILD_EXTRA_SYMBOLS only for external modules kbuild: modpost: include .*.cmd files only when targets exist kbuild: initialize CLANG_FLAGS correctly in the top Makefile kbuild: detect missing "WITH Linux-syscall-note" for uapi headers
2019-08-04Merge tag 'safesetid-maintainers-correction-5.3-rc2' of ↵Linus Torvalds
git://github.com/micah-morton/linux Pull SafeSetID maintainer update from Micah Morton: "Add entry in MAINTAINERS file for SafeSetID LSM" * tag 'safesetid-maintainers-correction-5.3-rc2' of git://github.com/micah-morton/linux: Add entry in MAINTAINERS file for SafeSetID LSM
2019-08-04kconfig: Clear "written" flag to avoid data lossM. Vefa Bicakci
Prior to this commit, starting nconfig, xconfig or gconfig, and saving the .config file more than once caused data loss, where a .config file that contained only comments would be written to disk starting from the second save operation. This bug manifests itself because the SYMBOL_WRITTEN flag is never cleared after the first call to conf_write, and subsequent calls to conf_write then skip all of the configuration symbols due to the SYMBOL_WRITTEN flag being set. This commit resolves this issue by clearing the SYMBOL_WRITTEN flag from all symbols before conf_write returns. Fixes: 8e2442a5f86e ("kconfig: fix missing choice values in auto.conf") Cc: linux-stable <stable@vger.kernel.org> # 4.19+ Signed-off-by: M. Vefa Bicakci <m.v.b@runbox.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-03Merge tag 'xtensa-20190803' of git://github.com/jcmvbkbc/linux-xtensaLinus Torvalds
Pull Xtensa fix from Max Filippov: "Fix build for xtensa cores with coprocessors that was broken by entry/return abstraction patch" * tag 'xtensa-20190803' of git://github.com/jcmvbkbc/linux-xtensa: xtensa: fix build for cores with coprocessors
2019-08-03Merge branch 'i2c/for-current-fixed' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux Pull i2c fixes from Wolfram Sang: "A set of driver fixes for the I2C subsystem" * 'i2c/for-current-fixed' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: i2c: s3c2410: Mark expected switch fall-through i2c: at91: fix clk_offset for sama5d2 i2c: at91: disable TXRDY interrupt after sending data i2c: iproc: Fix i2c master read more than 63 bytes eeprom: at24: make spd world-readable again
2019-08-03Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf tooling fixes from Thomas Gleixner: "A set of updates for perf tools and documentation: perf header: - Prevent a division by zero - Deal with an uninitialized warning proper libbpf: - Fix the missiong __WORDSIZE definition for musl & al UAPI headers: - Synchronize kernel headers Documentation: - Fix the memory units for perf.data size" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: libbpf: fix missing __WORDSIZE definition perf tools: Fix perf.data documentation units for memory size perf header: Fix use of unitialized value warning perf header: Fix divide by zero error if f_header.attr_size==0 tools headers UAPI: Sync if_link.h with the kernel tools headers UAPI: Sync sched.h with the kernel tools headers UAPI: Sync usbdevice_fs.h with the kernels to get new ioctl tools perf beauty: Fix usbdevfs_ioctl table generator to handle _IOC() tools headers UAPI: Update tools's copy of drm.h headers tools headers UAPI: Update tools's copy of mman.h headers tools headers UAPI: Update tools's copy of kvm.h headers tools include UAPI: Sync x86's syscalls_64.tbl and generic unistd.h to pick up clone3 and pidfd_open
2019-08-03Merge branch 'timers-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull vdso timer fixes from Thomas Gleixner: "A series of commits to deal with the regression caused by the generic VDSO implementation. The usage of clock_gettime64() for 32bit compat fallback syscalls caused seccomp filters to kill innocent processes because they only allow clock_gettime(). Handle the compat syscalls with clock_gettime() as before, which is not a functional problem for the VDSO as the legacy compat application interface is not y2038 safe anyway. It's just extra fallback code which needs to be implemented on every architecture. It's opt in for now so that it does not break the compile of already converted architectures in linux-next. Once these are fixed, the #ifdeffery goes away. So much for trying to be smart and reuse code..." * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: arm64: compat: vdso: Use legacy syscalls as fallback x86/vdso/32: Use 32bit syscall fallback lib/vdso/32: Provide legacy syscall fallbacks lib/vdso: Move fallback invocation to the callers lib/vdso/32: Remove inconsistent NULL pointer checks
2019-08-03Merge branch 'irq-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull irq fixes from Thomas Gleixner: "A small bunch of fixes from the irqchip department: - Fix a couple of UAF on error paths (RZA1, GICv3 ITS) - Fix iMX GPCv2 trigger setting - Add missing of_node_put() on error path in MBIGEN - Add another bunch of /* fall-through */ to silence warnings" * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: irqchip/renesas-rza1: Fix an use-after-free in rza1_irqc_probe() irqchip/irq-imx-gpcv2: Forward irq type to parent irqchip/irq-mbigen: Add of_node_put() before return irqchip/gic-v3-its: Free unused vpt_page when alloc vpe table fail irqchip/gic-v3: Mark expected switch fall-through
2019-08-03Merge tag 'xfs-5.3-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linuxLinus Torvalds
Pull xfs fixes from Darrick Wong: - Avoid leaking kernel stack contents to userspace - Fix a potential null pointer dereference in the dabtree scrub code * tag 'xfs-5.3-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: xfs: Fix possible null-pointer dereferences in xchk_da_btree_block_check_sibling() xfs: fix stack contents leakage in the v1 inumber ioctls
2019-08-03Merge branch 'akpm' (patches from Andrew)Linus Torvalds
Merge misc fixes from Andrew Morton: "17 fixes" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: drivers/acpi/scan.c: document why we don't need the device_hotplug_lock memremap: move from kernel/ to mm/ lib/test_meminit.c: use GFP_ATOMIC in RCU critical section asm-generic: fix -Wtype-limits compiler warnings cgroup: kselftest: relax fs_spec checks mm/memory_hotplug.c: remove unneeded return for void function mm/migrate.c: initialize pud_entry in migrate_vma() coredump: split pipe command whitespace before expanding template page flags: prioritize kasan bits over last-cpuid ubsan: build ubsan.c more conservatively kasan: remove clang version check for KASAN_STACK mm: compaction: avoid 100% CPU usage during compaction when a task is killed mm: migrate: fix reference check race between __find_get_block() and migration mm: vmscan: check if mem cgroup is disabled or not before calling memcg slab shrinker ocfs2: remove set but not used variable 'last_hash' Revert "kmemleak: allow to coexist with fault injection" kernel/signal.c: fix a kernel-doc markup
2019-08-03Merge tag 'riscv/for-v5.3-rc3' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux Pull RISC-V fixes from Paul Walmsley: "Three minor RISC-V-related changes for v5.3-rc3: - Add build ID to VDSO builds to avoid a double-free in perf when libelf isn't used - Align the RV64 defconfig to the output of "make savedefconfig" so subsequent defconfig patches don't get out of hand - Drop a superfluous DT property from the FU540 SoC DT data (since it must be already set in board data that includes it)" * tag 'riscv/for-v5.3-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: riscv: defconfig: align RV64 defconfig to the output of "make savedefconfig" riscv: dts: fu540-c000: drop "timebase-frequency" riscv: Fix perf record without libelf support
2019-08-03drivers/acpi/scan.c: document why we don't need the device_hotplug_lockDavid Hildenbrand
Let's document why the lock is not needed in acpi_scan_init(), right now this is not really obvious. [akpm@linux-foundation.org: fix tpyo] Link: http://lkml.kernel.org/r/20190731135306.31524-1-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-03memremap: move from kernel/ to mm/Christoph Hellwig
memremap.c implements MM functionality for ZONE_DEVICE, so it really should be in the mm/ directory, not the kernel/ one. Link: http://lkml.kernel.org/r/20190722094143.18387-1-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Acked-by: 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>
2019-08-03lib/test_meminit.c: use GFP_ATOMIC in RCU critical sectionAlexander Potapenko
kmalloc() shouldn't sleep while in RCU critical section, therefore use GFP_ATOMIC instead of GFP_KERNEL. The bug was spotted by the 0day kernel testing robot. Link: http://lkml.kernel.org/r/20190725121703.210874-1-glider@google.com Fixes: 7e659650cbda ("lib: introduce test_meminit module") Signed-off-by: Alexander Potapenko <glider@google.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reported-by: kernel test robot <lkp@intel.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-03asm-generic: fix -Wtype-limits compiler warningsQian Cai
Commit d66acc39c7ce ("bitops: Optimise get_order()") introduced a compilation warning because "rx_frag_size" is an "ushort" while PAGE_SHIFT here is 16. The commit changed the get_order() to be a multi-line macro where compilers insist to check all statements in the macro even when __builtin_constant_p(rx_frag_size) will return false as "rx_frag_size" is a module parameter. In file included from ./arch/powerpc/include/asm/page_64.h:107, from ./arch/powerpc/include/asm/page.h:242, from ./arch/powerpc/include/asm/mmu.h:132, from ./arch/powerpc/include/asm/lppaca.h:47, from ./arch/powerpc/include/asm/paca.h:17, from ./arch/powerpc/include/asm/current.h:13, from ./include/linux/thread_info.h:21, from ./arch/powerpc/include/asm/processor.h:39, from ./include/linux/prefetch.h:15, from drivers/net/ethernet/emulex/benet/be_main.c:14: drivers/net/ethernet/emulex/benet/be_main.c: In function 'be_rx_cqs_create': ./include/asm-generic/getorder.h:54:9: warning: comparison is always true due to limited range of data type [-Wtype-limits] (((n) < (1UL << PAGE_SHIFT)) ? 0 : \ ^ drivers/net/ethernet/emulex/benet/be_main.c:3138:33: note: in expansion of macro 'get_order' adapter->big_page_size = (1 << get_order(rx_frag_size)) * PAGE_SIZE; ^~~~~~~~~ Fix it by moving all of this multi-line macro into a proper function, and killing __get_order() off. [akpm@linux-foundation.org: remove __get_order() altogether] [cai@lca.pw: v2] Link: http://lkml.kernel.org/r/1564000166-31428-1-git-send-email-cai@lca.pw Link: http://lkml.kernel.org/r/1563914986-26502-1-git-send-email-cai@lca.pw Fixes: d66acc39c7ce ("bitops: Optimise get_order()") Signed-off-by: Qian Cai <cai@lca.pw> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Cc: David S. Miller <davem@davemloft.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: David Howells <dhowells@redhat.com> Cc: Jakub Jelinek <jakub@redhat.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Bill Wendling <morbo@google.com> Cc: James Y Knight <jyknight@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-03cgroup: kselftest: relax fs_spec checksChris Down
On my laptop most memcg kselftests were being skipped because it claimed cgroup v2 hierarchy wasn't mounted, but this isn't correct. Instead, it seems current systemd HEAD mounts it with the name "cgroup2" instead of "cgroup": % grep cgroup /proc/mounts cgroup2 /sys/fs/cgroup cgroup2 rw,nosuid,nodev,noexec,relatime,nsdelegate 0 0 I can't think of a reason to need to check fs_spec explicitly since it's arbitrary, so we can just rely on fs_vfstype. After these changes, `make TARGETS=cgroup kselftest` actually runs the cgroup v2 tests in more cases. Link: http://lkml.kernel.org/r/20190723210737.GA487@chrisdown.name Signed-off-by: Chris Down <chris@chrisdown.name> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-03mm/memory_hotplug.c: remove unneeded return for void functionWeitao Hou
return is unneeded in void function Link: http://lkml.kernel.org/r/20190723130814.21826-1-houweitaoo@gmail.com Signed-off-by: Weitao Hou <houweitaoo@gmail.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-03mm/migrate.c: initialize pud_entry in migrate_vma()Ralph Campbell
When CONFIG_MIGRATE_VMA_HELPER is enabled, migrate_vma() calls migrate_vma_collect() which initializes a struct mm_walk but didn't initialize mm_walk.pud_entry. (Found by code inspection) Use a C structure initialization to make sure it is set to NULL. Link: http://lkml.kernel.org/r/20190719233225.12243-1-rcampbell@nvidia.com Fixes: 8763cb45ab967 ("mm/migrate: new memory migration helper for use with device memory") Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: "Jérôme Glisse" <jglisse@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-03coredump: split pipe command whitespace before expanding templatePaul Wise
Save the offsets of the start of each argument to avoid having to update pointers to each argument after every corename krealloc and to avoid having to duplicate the memory for the dump command. Executable names containing spaces were previously being expanded from %e or %E and then split in the middle of the filename. This is incorrect behaviour since an argument list can represent arguments with spaces. The splitting could lead to extra arguments being passed to the core dump handler that it might have interpreted as options or ignored completely. Core dump handlers that are not aware of this Linux kernel issue will be using %e or %E without considering that it may be split and so they will be vulnerable to processes with spaces in their names breaking their argument list. If their internals are otherwise well written, such as if they are written in shell but quote arguments, they will work better after this change than before. If they are not well written, then there is a slight chance of breakage depending on the details of the code but they will already be fairly broken by the split filenames. Core dump handlers that are aware of this Linux kernel issue will be placing %e or %E as the last item in their core_pattern and then aggregating all of the remaining arguments into one, separated by spaces. Alternatively they will be obtaining the filename via other methods. Both of these will be compatible with the new arrangement. A side effect from this change is that unknown template types (for example %z) result in an empty argument to the dump handler instead of the argument being dropped. This is a desired change as: It is easier for dump handlers to process empty arguments than dropped ones, especially if they are written in shell or don't pass each template item with a preceding command-line option in order to differentiate between individual template types. Most core_patterns in the wild do not use options so they can confuse different template types (especially numeric ones) if an earlier one gets dropped in old kernels. If the kernel introduces a new template type and a core_pattern uses it, the core dump handler might not expect that the argument can be dropped in old kernels. For example, this can result in security issues when %d is dropped in old kernels. This happened with the corekeeper package in Debian and resulted in the interface between corekeeper and Linux having to be rewritten to use command-line options to differentiate between template types. The core_pattern for most core dump handlers is written by the handler author who would generally not insert unknown template types so this change should be compatible with all the core dump handlers that exist. Link: http://lkml.kernel.org/r/20190528051142.24939-1-pabs3@bonedaddy.net Fixes: 74aadce98605 ("core_pattern: allow passing of arguments to user mode helper when core_pattern is a pipe") Signed-off-by: Paul Wise <pabs3@bonedaddy.net> Reported-by: Jakub Wilk <jwilk@jwilk.net> [https://bugs.debian.org/924398] Reported-by: Paul Wise <pabs3@bonedaddy.net> [https://lore.kernel.org/linux-fsdevel/c8b7ecb8508895bf4adb62a748e2ea2c71854597.camel@bonedaddy.net/] Suggested-by: Jakub Wilk <jwilk@jwilk.net> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-03page flags: prioritize kasan bits over last-cpuidArnd Bergmann
ARM64 randdconfig builds regularly run into a build error, especially when NUMA_BALANCING and SPARSEMEM are enabled but not SPARSEMEM_VMEMMAP: #error "KASAN: not enough bits in page flags for tag" The last-cpuid bits are already contitional on the available space, so the result of the calculation is a bit random on whether they were already left out or not. Adding the kasan tag bits before last-cpuid makes it much more likely to end up with a successful build here, and should be reliable for randconfig at least, as long as that does not randomize NR_CPUS or NODES_SHIFT but uses the defaults. In order for the modified check to not trigger in the x86 vdso32 code where all constants are wrong (building with -m32), enclose all the definitions with an #ifdef. [arnd@arndb.de: build fix] Link: http://lkml.kernel.org/r/CAK8P3a3Mno1SWTcuAOT0Wa9VS15pdU6EfnkxLbDpyS55yO04+g@mail.gmail.com Link: http://lkml.kernel.org/r/20190722115520.3743282-1-arnd@arndb.de Link: https://lore.kernel.org/lkml/20190618095347.3850490-1-arnd@arndb.de/ Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-03ubsan: build ubsan.c more conservativelyArnd Bergmann
objtool points out several conditions that it does not like, depending on the combination with other configuration options and compiler variants: stack protector: lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch()+0xbf: call to __stack_chk_fail() with UACCESS enabled lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1()+0xbe: call to __stack_chk_fail() with UACCESS enabled stackleak plugin: lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch()+0x4a: call to stackleak_track_stack() with UACCESS enabled lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1()+0x4a: call to stackleak_track_stack() with UACCESS enabled kasan: lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch()+0x25: call to memcpy() with UACCESS enabled lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1()+0x25: call to memcpy() with UACCESS enabled The stackleak and kasan options just need to be disabled for this file as we do for other files already. For the stack protector, we already attempt to disable it, but this fails on clang because the check is mixed with the gcc specific -fno-conserve-stack option. According to Andrey Ryabinin, that option is not even needed, dropping it here fixes the stackprotector issue. Link: http://lkml.kernel.org/r/20190722125139.1335385-1-arnd@arndb.de Link: https://lore.kernel.org/lkml/20190617123109.667090-1-arnd@arndb.de/t/ Link: https://lore.kernel.org/lkml/20190722091050.2188664-1-arnd@arndb.de/t/ Fixes: d08965a27e84 ("x86/uaccess, ubsan: Fix UBSAN vs. SMAP") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.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>
2019-08-03kasan: remove clang version check for KASAN_STACKArnd Bergmann
asan-stack mode still uses dangerously large kernel stacks of tens of kilobytes in some drivers, and it does not seem that anyone is working on the clang bug. Turn it off for all clang versions to prevent users from accidentally enabling it once they update to clang-9, and to help automated build testing with clang-9. Link: https://bugs.llvm.org/show_bug.cgi?id=38809 Link: http://lkml.kernel.org/r/20190719200347.2596375-1-arnd@arndb.de Fixes: 6baec880d7a5 ("kasan: turn off asan-stack for clang-8 and earlier") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Mark Brown <broonie@kernel.org> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Qian Cai <cai@lca.pw> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-03mm: compaction: avoid 100% CPU usage during compaction when a task is killedMel Gorman
"howaboutsynergy" reported via kernel buzilla number 204165 that compact_zone_order was consuming 100% CPU during a stress test for prolonged periods of time. Specifically the following command, which should exit in 10 seconds, was taking an excessive time to finish while the CPU was pegged at 100%. stress -m 220 --vm-bytes 1000000000 --timeout 10 Tracing indicated a pattern as follows stress-3923 [007] 519.106208: mm_compaction_isolate_migratepages: range=(0x70bb80 ~ 0x70bb80) nr_scanned=0 nr_taken=0 stress-3923 [007] 519.106212: mm_compaction_isolate_migratepages: range=(0x70bb80 ~ 0x70bb80) nr_scanned=0 nr_taken=0 stress-3923 [007] 519.106216: mm_compaction_isolate_migratepages: range=(0x70bb80 ~ 0x70bb80) nr_scanned=0 nr_taken=0 stress-3923 [007] 519.106219: mm_compaction_isolate_migratepages: range=(0x70bb80 ~ 0x70bb80) nr_scanned=0 nr_taken=0 stress-3923 [007] 519.106223: mm_compaction_isolate_migratepages: range=(0x70bb80 ~ 0x70bb80) nr_scanned=0 nr_taken=0 stress-3923 [007] 519.106227: mm_compaction_isolate_migratepages: range=(0x70bb80 ~ 0x70bb80) nr_scanned=0 nr_taken=0 stress-3923 [007] 519.106231: mm_compaction_isolate_migratepages: range=(0x70bb80 ~ 0x70bb80) nr_scanned=0 nr_taken=0 stress-3923 [007] 519.106235: mm_compaction_isolate_migratepages: range=(0x70bb80 ~ 0x70bb80) nr_scanned=0 nr_taken=0 stress-3923 [007] 519.106238: mm_compaction_isolate_migratepages: range=(0x70bb80 ~ 0x70bb80) nr_scanned=0 nr_taken=0 stress-3923 [007] 519.106242: mm_compaction_isolate_migratepages: range=(0x70bb80 ~ 0x70bb80) nr_scanned=0 nr_taken=0 Note that compaction is entered in rapid succession while scanning and isolating nothing. The problem is that when a task that is compacting receives a fatal signal, it retries indefinitely instead of exiting while making no progress as a fatal signal is pending. It's not easy to trigger this condition although enabling zswap helps on the basis that the timing is altered. A very small window has to be hit for the problem to occur (signal delivered while compacting and isolating a PFN for migration that is not aligned to SWAP_CLUSTER_MAX). This was reproduced locally -- 16G single socket system, 8G swap, 30% zswap configured, vm-bytes 22000000000 using Colin Kings stress-ng implementation from github running in a loop until the problem hits). Tracing recorded the problem occurring almost 200K times in a short window. With this patch, the problem hit 4 times but the task existed normally instead of consuming CPU. This problem has existed for some time but it was made worse by commit cf66f0700c8f ("mm, compaction: do not consider a need to reschedule as contention"). Before that commit, if the same condition was hit then locks would be quickly contended and compaction would exit that way. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204165 Link: http://lkml.kernel.org/r/20190718085708.GE24383@techsingularity.net Fixes: cf66f0700c8f ("mm, compaction: do not consider a need to reschedule as contention") Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: <stable@vger.kernel.org> [5.1+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-03mm: migrate: fix reference check race between __find_get_block() and migrationJan Kara
buffer_migrate_page_norefs() can race with bh users in the following way: CPU1 CPU2 buffer_migrate_page_norefs() buffer_migrate_lock_buffers() checks bh refs spin_unlock(&mapping->private_lock) __find_get_block() spin_lock(&mapping->private_lock) grab bh ref spin_unlock(&mapping->private_lock) move page do bh work This can result in various issues like lost updates to buffers (i.e. metadata corruption) or use after free issues for the old page. This patch closes the race by holding mapping->private_lock while the mapping is being moved to a new page. Ordinarily, a reference can be taken outside of the private_lock using the per-cpu BH LRU but the references are checked and the LRU invalidated if necessary. The private_lock is held once the references are known so the buffer lookup slow path will spin on the private_lock. Between the page lock and private_lock, it should be impossible for other references to be acquired and updates to happen during the migration. A user had reported data corruption issues on a distribution kernel with a similar page migration implementation as mainline. The data corruption could not be reproduced with this patch applied. A small number of migration-intensive tests were run and no performance problems were noted. [mgorman@techsingularity.net: Changelog, removed tracing] Link: http://lkml.kernel.org/r/20190718090238.GF24383@techsingularity.net Fixes: 89cb0888ca14 "mm: migrate: provide buffer_migrate_page_norefs()" Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Cc: <stable@vger.kernel.org> [5.0+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>