linux.git/mm, branch v5.15-rc2 Linux kernel source tree memblock: introduce saner 'memblock_free_ptr()' interface 2021-09-14T20:23:22+00:00 Linus Torvalds torvalds@linux-foundation.org 2021-09-14T20:23:22+00:00 77e02cf57b6cff9919949defb7fd9b8ac16399a2 The boot-time allocation interface for memblock is a mess, with 'memblock_alloc()' returning a virtual pointer, but then you are supposed to free it with 'memblock_free()' that takes a _physical_ address. Not only is that all kinds of strange and illogical, but it actually causes bugs, when people then use it like a normal allocation function, and it fails spectacularly on a NULL pointer: https://lore.kernel.org/all/20210912140820.GD25450@xsang-OptiPlex-9020/ or just random memory corruption if the debug checks don't catch it: https://lore.kernel.org/all/61ab2d0c-3313-aaab-514c-e15b7aa054a0@suse.cz/ I really don't want to apply patches that treat the symptoms, when the fundamental cause is this horribly confusing interface. I started out looking at just automating a sane replacement sequence, but because of this mix or virtual and physical addresses, and because people have used the "__pa()" macro that can take either a regular kernel pointer, or just the raw "unsigned long" address, it's all quite messy. So this just introduces a new saner interface for freeing a virtual address that was allocated using 'memblock_alloc()', and that was kept as a regular kernel pointer. And then it converts a couple of users that are obvious and easy to test, including the 'xbc_nodes' case in lib/bootconfig.c that caused problems. Reported-by: kernel test robot <oliver.sang@intel.com> Fixes: 40caa127f3c7 ("init: bootconfig: Remove all bootconfig data when the init memory is removed") Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
The boot-time allocation interface for memblock is a mess, with
'memblock_alloc()' returning a virtual pointer, but then you are
supposed to free it with 'memblock_free()' that takes a _physical_
address.

Not only is that all kinds of strange and illogical, but it actually
causes bugs, when people then use it like a normal allocation function,
and it fails spectacularly on a NULL pointer:

   https://lore.kernel.org/all/20210912140820.GD25450@xsang-OptiPlex-9020/

or just random memory corruption if the debug checks don't catch it:

   https://lore.kernel.org/all/61ab2d0c-3313-aaab-514c-e15b7aa054a0@suse.cz/

I really don't want to apply patches that treat the symptoms, when the
fundamental cause is this horribly confusing interface.

I started out looking at just automating a sane replacement sequence,
but because of this mix or virtual and physical addresses, and because
people have used the "__pa()" macro that can take either a regular
kernel pointer, or just the raw "unsigned long" address, it's all quite
messy.

So this just introduces a new saner interface for freeing a virtual
address that was allocated using 'memblock_alloc()', and that was kept
as a regular kernel pointer.  And then it converts a couple of users
that are obvious and easy to test, including the 'xbc_nodes' case in
lib/bootconfig.c that caused problems.

Reported-by: kernel test robot <oliver.sang@intel.com>
Fixes: 40caa127f3c7 ("init: bootconfig: Remove all bootconfig data when the init memory is removed")
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge branch 'gcc-min-version-5.1' (make gcc-5.1 the minimum version) 2021-09-13T17:43:04+00:00 Linus Torvalds torvalds@linux-foundation.org 2021-09-13T17:43:04+00:00 316346243be6df12799c0b64b788e06bad97c30b Merge patch series from Nick Desaulniers to update the minimum gcc version to 5.1. This is some of the left-overs from the merge window that I didn't want to deal with yesterday, so it comes in after -rc1 but was sent before. Gcc-4.9 support has been an annoyance for some time, and with -Werror I had the choice of applying a fairly big patch from Kees Cook to remove a fair number of initializer warnings (still leaving some), or this patch series from Nick that just removes the source of the problem. The initializer cleanups might still be worth it regardless, but honestly, I preferred just tackling the problem with gcc-4.9 head-on. We've been more aggressiuve about no longer having to care about compilers that were released a long time ago, and I think it's been a good thing. I added a couple of patches on top to sort out a few left-overs now that we no longer support gcc-4.x. As noted by Arnd, as a result of this minimum compiler version upgrade we can probably change our use of '--std=gnu89' to '--std=gnu11', and finally start using local loop declarations etc. But this series does _not_ yet do that. Link: https://lore.kernel.org/all/20210909182525.372ee687@canb.auug.org.au/ Link: https://lore.kernel.org/lkml/CAK7LNASs6dvU6D3jL2GG3jW58fXfaj6VNOe55NJnTB8UPuk2pA@mail.gmail.com/ Link: https://github.com/ClangBuiltLinux/linux/issues/1438 * emailed patches from Nick Desaulniers <ndesaulniers@google.com>: Drop some straggling mentions of gcc-4.9 as being stale compiler_attributes.h: drop __has_attribute() support for gcc4 vmlinux.lds.h: remove old check for GCC 4.9 compiler-gcc.h: drop checks for older GCC versions Makefile: drop GCC < 5 -fno-var-tracking-assignments workaround arm64: remove GCC version check for ARCH_SUPPORTS_INT128 powerpc: remove GCC version check for UPD_CONSTR riscv: remove Kconfig check for GCC version for ARCH_RV64I Kconfig.debug: drop GCC 5+ version check for DWARF5 mm/ksm: remove old GCC 4.9+ check compiler.h: drop fallback overflow checkers Documentation: raise minimum supported version of GCC to 5.1 
Merge patch series from Nick Desaulniers to update the minimum gcc
version to 5.1.

This is some of the left-overs from the merge window that I didn't want
to deal with yesterday, so it comes in after -rc1 but was sent before.

Gcc-4.9 support has been an annoyance for some time, and with -Werror I
had the choice of applying a fairly big patch from Kees Cook to remove a
fair number of initializer warnings (still leaving some), or this patch
series from Nick that just removes the source of the problem.

The initializer cleanups might still be worth it regardless, but
honestly, I preferred just tackling the problem with gcc-4.9 head-on.
We've been more aggressiuve about no longer having to care about
compilers that were released a long time ago, and I think it's been a
good thing.

I added a couple of patches on top to sort out a few left-overs now that
we no longer support gcc-4.x.

As noted by Arnd, as a result of this minimum compiler version upgrade
we can probably change our use of '--std=gnu89' to '--std=gnu11', and
finally start using local loop declarations etc.  But this series does
_not_ yet do that.

Link: https://lore.kernel.org/all/20210909182525.372ee687@canb.auug.org.au/
Link: https://lore.kernel.org/lkml/CAK7LNASs6dvU6D3jL2GG3jW58fXfaj6VNOe55NJnTB8UPuk2pA@mail.gmail.com/
Link: https://github.com/ClangBuiltLinux/linux/issues/1438

* emailed patches from Nick Desaulniers <ndesaulniers@google.com>:
  Drop some straggling mentions of gcc-4.9 as being stale
  compiler_attributes.h: drop __has_attribute() support for gcc4
  vmlinux.lds.h: remove old check for GCC 4.9
  compiler-gcc.h: drop checks for older GCC versions
  Makefile: drop GCC < 5 -fno-var-tracking-assignments workaround
  arm64: remove GCC version check for ARCH_SUPPORTS_INT128
  powerpc: remove GCC version check for UPD_CONSTR
  riscv: remove Kconfig check for GCC version for ARCH_RV64I
  Kconfig.debug: drop GCC 5+ version check for DWARF5
  mm/ksm: remove old GCC 4.9+ check
  compiler.h: drop fallback overflow checkers
  Documentation: raise minimum supported version of GCC to 5.1
mm/ksm: remove old GCC 4.9+ check 2021-09-13T17:18:28+00:00 Nick Desaulniers ndesaulniers@google.com 2021-09-10T23:40:40+00:00 adac17e3f61f54927b961d97bd303dd5795a307b The minimum supported version of GCC has been raised to GCC 5.1. Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
The minimum supported version of GCC has been raised to GCC 5.1.

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2021-09-09T20:25:49+00:00 Linus Torvalds torvalds@linux-foundation.org 2021-09-09T20:25:49+00:00 35776f10513c0d523c5dd2f1b415f642497779e2 Pull ARM development updates from Russell King: - Rename "mod_init" and "mod_exit" so that initcall debug output is actually useful (Randy Dunlap) - Update maintainers entries for linux-arm-kernel to indicate it is moderated for non-subscribers (Randy Dunlap) - Move install rules to arch/arm/Makefile (Masahiro Yamada) - Drop unnecessary ARCH_NR_GPIOS definition (Linus Walleij) - Don't warn about atags_to_fdt() stack size (David Heidelberg) - Speed up unaligned copy_{from,to}_kernel_nofault (Arnd Bergmann) - Get rid of set_fs() usage (Arnd Bergmann) - Remove checks for GCC prior to v4.6 (Geert Uytterhoeven) * tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: ARM: 9118/1: div64: Remove always-true __div64_const32_is_OK() duplicate ARM: 9117/1: asm-generic: div64: Remove always-true __div64_const32_is_OK() ARM: 9116/1: unified: Remove check for gcc < 4 ARM: 9110/1: oabi-compat: fix oabi epoll sparse warning ARM: 9113/1: uaccess: remove set_fs() implementation ARM: 9112/1: uaccess: add __{get,put}_kernel_nofault ARM: 9111/1: oabi-compat: rework fcntl64() emulation ARM: 9114/1: oabi-compat: rework sys_semtimedop emulation ARM: 9108/1: oabi-compat: rework epoll_wait/epoll_pwait emulation ARM: 9107/1: syscall: always store thread_info->abi_syscall ARM: 9109/1: oabi-compat: add epoll_pwait handler ARM: 9106/1: traps: use get_kernel_nofault instead of set_fs() ARM: 9115/1: mm/maccess: fix unaligned copy_{from,to}_kernel_nofault ARM: 9105/1: atags_to_fdt: don't warn about stack size ARM: 9103/1: Drop ARCH_NR_GPIOS definition ARM: 9102/1: move theinstall rules to arch/arm/Makefile ARM: 9100/1: MAINTAINERS: mark all linux-arm-kernel@infradead list as moderated ARM: 9099/1: crypto: rename 'mod_init' & 'mod_exit' functions to be module-specific 
Pull ARM development updates from Russell King:

 - Rename "mod_init" and "mod_exit" so that initcall debug output is
   actually useful (Randy Dunlap)

 - Update maintainers entries for linux-arm-kernel to indicate it is
   moderated for non-subscribers (Randy Dunlap)

 - Move install rules to arch/arm/Makefile (Masahiro Yamada)

 - Drop unnecessary ARCH_NR_GPIOS definition (Linus Walleij)

 - Don't warn about atags_to_fdt() stack size (David Heidelberg)

 - Speed up unaligned copy_{from,to}_kernel_nofault (Arnd Bergmann)

 - Get rid of set_fs() usage (Arnd Bergmann)

 - Remove checks for GCC prior to v4.6 (Geert Uytterhoeven)

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 9118/1: div64: Remove always-true __div64_const32_is_OK() duplicate
  ARM: 9117/1: asm-generic: div64: Remove always-true __div64_const32_is_OK()
  ARM: 9116/1: unified: Remove check for gcc < 4
  ARM: 9110/1: oabi-compat: fix oabi epoll sparse warning
  ARM: 9113/1: uaccess: remove set_fs() implementation
  ARM: 9112/1: uaccess: add __{get,put}_kernel_nofault
  ARM: 9111/1: oabi-compat: rework fcntl64() emulation
  ARM: 9114/1: oabi-compat: rework sys_semtimedop emulation
  ARM: 9108/1: oabi-compat: rework epoll_wait/epoll_pwait emulation
  ARM: 9107/1: syscall: always store thread_info->abi_syscall
  ARM: 9109/1: oabi-compat: add epoll_pwait handler
  ARM: 9106/1: traps: use get_kernel_nofault instead of set_fs()
  ARM: 9115/1: mm/maccess: fix unaligned copy_{from,to}_kernel_nofault
  ARM: 9105/1: atags_to_fdt: don't warn about stack size
  ARM: 9103/1: Drop ARCH_NR_GPIOS definition
  ARM: 9102/1: move theinstall rules to arch/arm/Makefile
  ARM: 9100/1: MAINTAINERS: mark all linux-arm-kernel@infradead list as moderated
  ARM: 9099/1: crypto: rename 'mod_init' & 'mod_exit' functions to be module-specific
Merge branches 'akpm' and 'akpm-hotfixes' (patches from Andrew) 2021-09-09T01:52:05+00:00 Linus Torvalds torvalds@linux-foundation.org 2021-09-09T01:52:05+00:00 a3fa7a101dcff93791d1b1bdb3affcad1410c8c1 Merge yet more updates and hotfixes from Andrew Morton: "Post-linux-next material, based upon latest upstream to catch the now-merged dependencies: - 10 patches. Subsystems affected by this patch series: mm (vmstat and migration) and compat. And bunch of hotfixes, mostly cc:stable: - 8 patches. Subsystems affected by this patch series: mm (hmm, hugetlb, vmscan, pagealloc, pagemap, kmemleak, mempolicy, and memblock)" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: arch: remove compat_alloc_user_space compat: remove some compat entry points mm: simplify compat numa syscalls mm: simplify compat_sys_move_pages kexec: avoid compat_alloc_user_space kexec: move locking into do_kexec_load mm: migrate: change to use bool type for 'page_was_mapped' mm: migrate: fix the incorrect function name in comments mm: migrate: introduce a local variable to get the number of pages mm/vmstat: protect per cpu variables with preempt disable on RT * emailed hotfixes from Andrew Morton <akpm@linux-foundation.org>: nds32/setup: remove unused memblock_region variable in setup_memory() mm/mempolicy: fix a race between offset_il_node and mpol_rebind_task mm/kmemleak: allow __GFP_NOLOCKDEP passed to kmemleak's gfp mmap_lock: change trace and locking order mm/page_alloc.c: avoid accessing uninitialized pcp page migratetype mm,vmscan: fix divide by zero in get_scan_count mm/hugetlb: initialize hugetlb_usage in mm_init mm/hmm: bypass devmap pte when all pfn requested flags are fulfilled 
Merge yet more updates and hotfixes from Andrew Morton:
 "Post-linux-next material, based upon latest upstream to catch the
  now-merged dependencies:

   - 10 patches.

     Subsystems affected by this patch series: mm (vmstat and migration)
     and compat.

  And bunch of hotfixes, mostly cc:stable:

   - 8 patches.

     Subsystems affected by this patch series: mm (hmm, hugetlb, vmscan,
     pagealloc, pagemap, kmemleak, mempolicy, and memblock)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  arch: remove compat_alloc_user_space
  compat: remove some compat entry points
  mm: simplify compat numa syscalls
  mm: simplify compat_sys_move_pages
  kexec: avoid compat_alloc_user_space
  kexec: move locking into do_kexec_load
  mm: migrate: change to use bool type for 'page_was_mapped'
  mm: migrate: fix the incorrect function name in comments
  mm: migrate: introduce a local variable to get the number of pages
  mm/vmstat: protect per cpu variables with preempt disable on RT

* emailed hotfixes from Andrew Morton <akpm@linux-foundation.org>:
  nds32/setup: remove unused memblock_region variable in setup_memory()
  mm/mempolicy: fix a race between offset_il_node and mpol_rebind_task
  mm/kmemleak: allow __GFP_NOLOCKDEP passed to kmemleak's gfp
  mmap_lock: change trace and locking order
  mm/page_alloc.c: avoid accessing uninitialized pcp page migratetype
  mm,vmscan: fix divide by zero in get_scan_count
  mm/hugetlb: initialize hugetlb_usage in mm_init
  mm/hmm: bypass devmap pte when all pfn requested flags are fulfilled
mm/mempolicy: fix a race between offset_il_node and mpol_rebind_task 2021-09-09T01:45:53+00:00 yanghui yanghui.def@bytedance.com 2021-09-09T01:10:20+00:00 276aeee1c5fc00df700f0782060beae126600472 Servers happened below panic: Kernel version:5.4.56 BUG: unable to handle page fault for address: 0000000000002c48 RIP: 0010:__next_zones_zonelist+0x1d/0x40 Call Trace: __alloc_pages_nodemask+0x277/0x310 alloc_page_interleave+0x13/0x70 handle_mm_fault+0xf99/0x1390 __do_page_fault+0x288/0x500 do_page_fault+0x30/0x110 page_fault+0x3e/0x50 The reason for the panic is that MAX_NUMNODES is passed in the third parameter in __alloc_pages_nodemask(preferred_nid). So access to zonelist->zoneref->zone_idx in __next_zones_zonelist will cause a panic. In offset_il_node(), first_node() returns nid from pol->v.nodes, after this other threads may chang pol->v.nodes before next_node(). This race condition will let next_node return MAX_NUMNODES. So put pol->nodes in a local variable. The race condition is between offset_il_node and cpuset_change_task_nodemask: CPU0: CPU1: alloc_pages_vma() interleave_nid(pol,) offset_il_node(pol,) first_node(pol->v.nodes) cpuset_change_task_nodemask //nodes==0xc mpol_rebind_task mpol_rebind_policy mpol_rebind_nodemask(pol,nodes) //nodes==0x3 next_node(nid, pol->v.nodes)//return MAX_NUMNODES Link: https://lkml.kernel.org/r/20210906034658.48721-1-yanghui.def@bytedance.com Signed-off-by: yanghui <yanghui.def@bytedance.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Servers happened below panic:

  Kernel version:5.4.56
  BUG: unable to handle page fault for address: 0000000000002c48
  RIP: 0010:__next_zones_zonelist+0x1d/0x40
  Call Trace:
    __alloc_pages_nodemask+0x277/0x310
    alloc_page_interleave+0x13/0x70
    handle_mm_fault+0xf99/0x1390
    __do_page_fault+0x288/0x500
    do_page_fault+0x30/0x110
    page_fault+0x3e/0x50

The reason for the panic is that MAX_NUMNODES is passed in the third
parameter in __alloc_pages_nodemask(preferred_nid).  So access to
zonelist->zoneref->zone_idx in __next_zones_zonelist will cause a panic.

In offset_il_node(), first_node() returns nid from pol->v.nodes, after
this other threads may chang pol->v.nodes before next_node().  This race
condition will let next_node return MAX_NUMNODES.  So put pol->nodes in
a local variable.

The race condition is between offset_il_node and cpuset_change_task_nodemask:

  CPU0:                                     CPU1:
  alloc_pages_vma()
    interleave_nid(pol,)
      offset_il_node(pol,)
        first_node(pol->v.nodes)            cpuset_change_task_nodemask
                        //nodes==0xc          mpol_rebind_task
                                                mpol_rebind_policy
                                                  mpol_rebind_nodemask(pol,nodes)
                        //nodes==0x3
        next_node(nid, pol->v.nodes)//return MAX_NUMNODES

Link: https://lkml.kernel.org/r/20210906034658.48721-1-yanghui.def@bytedance.com
Signed-off-by: yanghui <yanghui.def@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/kmemleak: allow __GFP_NOLOCKDEP passed to kmemleak's gfp 2021-09-09T01:45:53+00:00 Naohiro Aota naohiro.aota@wdc.com 2021-09-09T01:10:17+00:00 79d3705040c3b41075f894fdeeebdcbb46550c63 In a memory pressure situation, I'm seeing the lockdep WARNING below. Actually, this is similar to a known false positive which is already addressed by commit 6dcde60efd94 ("xfs: more lockdep whackamole with kmem_alloc*"). This warning still persists because it's not from kmalloc() itself but from an allocation for kmemleak object. While kmalloc() itself suppress the warning with __GFP_NOLOCKDEP, gfp_kmemleak_mask() is dropping the flag for the kmemleak's allocation. Allow __GFP_NOLOCKDEP to be passed to kmemleak's allocation, so that the warning for it is also suppressed. ====================================================== WARNING: possible circular locking dependency detected 5.14.0-rc7-BTRFS-ZNS+ #37 Not tainted ------------------------------------------------------ kswapd0/288 is trying to acquire lock: ffff88825ab45df0 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_ilock+0x8a/0x250 but task is already holding lock: ffffffff848cc1e0 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: fs_reclaim_acquire+0x112/0x160 kmem_cache_alloc+0x48/0x400 create_object.isra.0+0x42/0xb10 kmemleak_alloc+0x48/0x80 __kmalloc+0x228/0x440 kmem_alloc+0xd3/0x2b0 kmem_alloc_large+0x5a/0x1c0 xfs_attr_copy_value+0x112/0x190 xfs_attr_shortform_getvalue+0x1fc/0x300 xfs_attr_get_ilocked+0x125/0x170 xfs_attr_get+0x329/0x450 xfs_get_acl+0x18d/0x430 get_acl.part.0+0xb6/0x1e0 posix_acl_xattr_get+0x13a/0x230 vfs_getxattr+0x21d/0x270 getxattr+0x126/0x310 __x64_sys_fgetxattr+0x1a6/0x2a0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (&xfs_nondir_ilock_class){++++}-{3:3}: __lock_acquire+0x2c0f/0x5a00 lock_acquire+0x1a1/0x4b0 down_read_nested+0x50/0x90 xfs_ilock+0x8a/0x250 xfs_can_free_eofblocks+0x34f/0x570 xfs_inactive+0x411/0x520 xfs_fs_destroy_inode+0x2c8/0x710 destroy_inode+0xc5/0x1a0 evict+0x444/0x620 dispose_list+0xfe/0x1c0 prune_icache_sb+0xdc/0x160 super_cache_scan+0x31e/0x510 do_shrink_slab+0x337/0x8e0 shrink_slab+0x362/0x5c0 shrink_node+0x7a7/0x1a40 balance_pgdat+0x64e/0xfe0 kswapd+0x590/0xa80 kthread+0x38c/0x460 ret_from_fork+0x22/0x30 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&xfs_nondir_ilock_class); lock(fs_reclaim); lock(&xfs_nondir_ilock_class); *** DEADLOCK *** 3 locks held by kswapd0/288: #0: ffffffff848cc1e0 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30 #1: ffffffff848a08d8 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0x269/0x5c0 #2: ffff8881a7a820e8 (&type->s_umount_key#60){++++}-{3:3}, at: super_cache_scan+0x5a/0x510 Link: https://lkml.kernel.org/r/20210907055659.3182992-1-naohiro.aota@wdc.com Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Cc: "Darrick J . Wong" <djwong@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
In a memory pressure situation, I'm seeing the lockdep WARNING below.
Actually, this is similar to a known false positive which is already
addressed by commit 6dcde60efd94 ("xfs: more lockdep whackamole with
kmem_alloc*").

This warning still persists because it's not from kmalloc() itself but
from an allocation for kmemleak object.  While kmalloc() itself suppress
the warning with __GFP_NOLOCKDEP, gfp_kmemleak_mask() is dropping the
flag for the kmemleak's allocation.

Allow __GFP_NOLOCKDEP to be passed to kmemleak's allocation, so that the
warning for it is also suppressed.

  ======================================================
  WARNING: possible circular locking dependency detected
  5.14.0-rc7-BTRFS-ZNS+ #37 Not tainted
  ------------------------------------------------------
  kswapd0/288 is trying to acquire lock:
  ffff88825ab45df0 (&xfs_nondir_ilock_class){++++}-{3:3}, at: xfs_ilock+0x8a/0x250

  but task is already holding lock:
  ffffffff848cc1e0 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #1 (fs_reclaim){+.+.}-{0:0}:
         fs_reclaim_acquire+0x112/0x160
         kmem_cache_alloc+0x48/0x400
         create_object.isra.0+0x42/0xb10
         kmemleak_alloc+0x48/0x80
         __kmalloc+0x228/0x440
         kmem_alloc+0xd3/0x2b0
         kmem_alloc_large+0x5a/0x1c0
         xfs_attr_copy_value+0x112/0x190
         xfs_attr_shortform_getvalue+0x1fc/0x300
         xfs_attr_get_ilocked+0x125/0x170
         xfs_attr_get+0x329/0x450
         xfs_get_acl+0x18d/0x430
         get_acl.part.0+0xb6/0x1e0
         posix_acl_xattr_get+0x13a/0x230
         vfs_getxattr+0x21d/0x270
         getxattr+0x126/0x310
         __x64_sys_fgetxattr+0x1a6/0x2a0
         do_syscall_64+0x3b/0x90
         entry_SYSCALL_64_after_hwframe+0x44/0xae

  -> #0 (&xfs_nondir_ilock_class){++++}-{3:3}:
         __lock_acquire+0x2c0f/0x5a00
         lock_acquire+0x1a1/0x4b0
         down_read_nested+0x50/0x90
         xfs_ilock+0x8a/0x250
         xfs_can_free_eofblocks+0x34f/0x570
         xfs_inactive+0x411/0x520
         xfs_fs_destroy_inode+0x2c8/0x710
         destroy_inode+0xc5/0x1a0
         evict+0x444/0x620
         dispose_list+0xfe/0x1c0
         prune_icache_sb+0xdc/0x160
         super_cache_scan+0x31e/0x510
         do_shrink_slab+0x337/0x8e0
         shrink_slab+0x362/0x5c0
         shrink_node+0x7a7/0x1a40
         balance_pgdat+0x64e/0xfe0
         kswapd+0x590/0xa80
         kthread+0x38c/0x460
         ret_from_fork+0x22/0x30

  other info that might help us debug this:
   Possible unsafe locking scenario:
         CPU0                    CPU1
         ----                    ----
    lock(fs_reclaim);
                                 lock(&xfs_nondir_ilock_class);
                                 lock(fs_reclaim);
    lock(&xfs_nondir_ilock_class);

   *** DEADLOCK ***
  3 locks held by kswapd0/288:
   #0: ffffffff848cc1e0 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30
   #1: ffffffff848a08d8 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0x269/0x5c0
   #2: ffff8881a7a820e8 (&type->s_umount_key#60){++++}-{3:3}, at: super_cache_scan+0x5a/0x510

Link: https://lkml.kernel.org/r/20210907055659.3182992-1-naohiro.aota@wdc.com
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/page_alloc.c: avoid accessing uninitialized pcp page migratetype 2021-09-09T01:45:53+00:00 Miaohe Lin linmiaohe@huawei.com 2021-09-09T01:10:11+00:00 053cfda102306a3394012f9fe2594811c34925e4 If it's not prepared to free unref page, the pcp page migratetype is unset. Thus we will get rubbish from get_pcppage_migratetype() and might list_del(&page->lru) again after it's already deleted from the list leading to grumble about data corruption. Link: https://lkml.kernel.org/r/20210902115447.57050-1-linmiaohe@huawei.com Fixes: df1acc856923 ("mm/page_alloc: avoid conflating IRQs disabled with zone->lock") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
If it's not prepared to free unref page, the pcp page migratetype is
unset.  Thus we will get rubbish from get_pcppage_migratetype() and
might list_del(&page->lru) again after it's already deleted from the list
leading to grumble about data corruption.

Link: https://lkml.kernel.org/r/20210902115447.57050-1-linmiaohe@huawei.com
Fixes: df1acc856923 ("mm/page_alloc: avoid conflating IRQs disabled with zone->lock")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm,vmscan: fix divide by zero in get_scan_count 2021-09-09T01:45:53+00:00 Rik van Riel riel@surriel.com 2021-09-09T01:10:08+00:00 32d4f4b782bb8f0ceb78c6b5dc46eb577ae25bf7 Commit f56ce412a59d ("mm: memcontrol: fix occasional OOMs due to proportional memory.low reclaim") introduced a divide by zero corner case when oomd is being used in combination with cgroup memory.low protection. When oomd decides to kill a cgroup, it will force the cgroup memory to be reclaimed after killing the tasks, by writing to the memory.max file for that cgroup, forcing the remaining page cache and reclaimable slab to be reclaimed down to zero. Previously, on cgroups with some memory.low protection that would result in the memory being reclaimed down to the memory.low limit, or likely not at all, having the page cache reclaimed asynchronously later. With f56ce412a59d the oomd write to memory.max tries to reclaim all the way down to zero, which may race with another reclaimer, to the point of ending up with the divide by zero below. This patch implements the obvious fix. Link: https://lkml.kernel.org/r/20210826220149.058089c6@imladris.surriel.com Fixes: f56ce412a59d ("mm: memcontrol: fix occasional OOMs due to proportional memory.low reclaim") Signed-off-by: Rik van Riel <riel@surriel.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Chris Down <chris@chrisdown.name> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Commit f56ce412a59d ("mm: memcontrol: fix occasional OOMs due to
proportional memory.low reclaim") introduced a divide by zero corner
case when oomd is being used in combination with cgroup memory.low
protection.

When oomd decides to kill a cgroup, it will force the cgroup memory to
be reclaimed after killing the tasks, by writing to the memory.max file
for that cgroup, forcing the remaining page cache and reclaimable slab
to be reclaimed down to zero.

Previously, on cgroups with some memory.low protection that would result
in the memory being reclaimed down to the memory.low limit, or likely
not at all, having the page cache reclaimed asynchronously later.

With f56ce412a59d the oomd write to memory.max tries to reclaim all the
way down to zero, which may race with another reclaimer, to the point of
ending up with the divide by zero below.

This patch implements the obvious fix.

Link: https://lkml.kernel.org/r/20210826220149.058089c6@imladris.surriel.com
Fixes: f56ce412a59d ("mm: memcontrol: fix occasional OOMs due to proportional memory.low reclaim")
Signed-off-by: Rik van Riel <riel@surriel.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/hmm: bypass devmap pte when all pfn requested flags are fulfilled 2021-09-09T01:45:52+00:00 Li Zhijian lizhijian@cn.fujitsu.com 2021-09-09T01:10:02+00:00 4b42fb213678d2b6a9eeea92a9be200f23e49583 Previously, we noticed the one rpma example was failed[1] since commit 36f30e486dce ("IB/core: Improve ODP to use hmm_range_fault()"), where it will use ODP feature to do RDMA WRITE between fsdax files. After digging into the code, we found hmm_vma_handle_pte() will still return EFAULT even though all the its requesting flags has been fulfilled. That's because a DAX page will be marked as (_PAGE_SPECIAL | PAGE_DEVMAP) by pte_mkdevmap(). Link: https://github.com/pmem/rpma/issues/1142 [1] Link: https://lkml.kernel.org/r/20210830094232.203029-1-lizhijian@cn.fujitsu.com Fixes: 405506274922 ("mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling") Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Previously, we noticed the one rpma example was failed[1] since commit
36f30e486dce ("IB/core: Improve ODP to use hmm_range_fault()"), where it
will use ODP feature to do RDMA WRITE between fsdax files.

After digging into the code, we found hmm_vma_handle_pte() will still
return EFAULT even though all the its requesting flags has been
fulfilled.  That's because a DAX page will be marked as (_PAGE_SPECIAL |
PAGE_DEVMAP) by pte_mkdevmap().

Link: https://github.com/pmem/rpma/issues/1142 [1]
Link: https://lkml.kernel.org/r/20210830094232.203029-1-lizhijian@cn.fujitsu.com
Fixes: 405506274922 ("mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling")
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>