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Roman Gushchin b43a9e76b4 writeback, cgroup: remove wb from offline list before releasing refcnt 
Boyang reported that the commit c22d70a162d3 ("writeback, cgroup:
release dying cgwbs by switching attached inodes") causes the kernel to
crash while running xfstests generic/256 on ext4 on aarch64 and ppc64le.

  run fstests generic/256 at 2021-07-12 05:41:40
  EXT4-fs (vda3): mounted filesystem with ordered data mode. Opts: . Quota mode: none.
  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
  Mem abort info:
     ESR = 0x96000005
     EC = 0x25: DABT (current EL), IL = 32 bits
     SET = 0, FnV = 0
     EA = 0, S1PTW = 0
     FSC = 0x05: level 1 translation fault
  Data abort info:
     ISV = 0, ISS = 0x00000005
     CM = 0, WnR = 0
  user pgtable: 64k pages, 48-bit VAs, pgdp=00000000b0502000
  [0000000000000000] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000
  Internal error: Oops: 96000005 [#1] SMP
  Modules linked in: dm_flakey dm_snapshot dm_bufio dm_zero dm_mod loop tls rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache netfs rfkill sunrpc ext4 vfat fat mbcache jbd2 drm fuse xfs libcrc32c crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce virtio_blk virtio_net net_failover virtio_console failover virtio_mmio aes_neon_bs [last unloaded: scsi_debug]
  CPU: 0 PID: 408468 Comm: kworker/u8:5 Tainted: G X --------- ---  5.14.0-0.rc1.15.bx.el9.aarch64 #1
  Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
  Workqueue: events_unbound cleanup_offline_cgwbs_workfn
  pstate: 004000c5 (nzcv daIF +PAN -UAO -TCO BTYPE=--)
  pc : cleanup_offline_cgwbs_workfn+0x320/0x394
  lr : cleanup_offline_cgwbs_workfn+0xe0/0x394
  sp : ffff80001554fd10
  x29: ffff80001554fd10 x28: 0000000000000000 x27: 0000000000000001
  x26: 0000000000000000 x25: 00000000000000e0 x24: ffffd2a2fbe671a8
  x23: ffff80001554fd88 x22: ffffd2a2fbe67198 x21: ffffd2a2fc25a730
  x20: ffff210412bc3000 x19: ffff210412bc3280 x18: 0000000000000000
  x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
  x14: 0000000000000000 x13: 0000000000000030 x12: 0000000000000040
  x11: ffff210481572238 x10: ffff21048157223a x9 : ffffd2a2fa276c60
  x8 : ffff210484106b60 x7 : 0000000000000000 x6 : 000000000007d18a
  x5 : ffff210416a86400 x4 : ffff210412bc0280 x3 : 0000000000000000
  x2 : ffff80001554fd88 x1 : ffff210412bc0280 x0 : 0000000000000003
  Call trace:
     cleanup_offline_cgwbs_workfn+0x320/0x394
     process_one_work+0x1f4/0x4b0
     worker_thread+0x184/0x540
     kthread+0x114/0x120
     ret_from_fork+0x10/0x18
  Code: d63f0020 97f99963 17ffffa6 f8588263 (f9400061)
  ---[ end trace e250fe289272792a ]---
  Kernel panic - not syncing: Oops: Fatal exception
  SMP: stopping secondary CPUs
  SMP: failed to stop secondary CPUs 0-2
  Kernel Offset: 0x52a2e9fa0000 from 0xffff800010000000
  PHYS_OFFSET: 0xfff0defca0000000
  CPU features: 0x00200251,23200840
  Memory Limit: none
  ---[ end Kernel panic - not syncing: Oops: Fatal exception ]---

The problem happens when cgwb_release_workfn() races with
cleanup_offline_cgwbs_workfn(): wb_tryget() in
cleanup_offline_cgwbs_workfn() can be called after percpu_ref_exit() is
cgwb_release_workfn(), which is basically a use-after-free error.

Fix the problem by making removing the writeback structure from the
offline list before releasing the percpu reference counter.  It will
guarantee that cleanup_offline_cgwbs_workfn() will not see and not
access writeback structures which are about to be released.

Link: https://lkml.kernel.org/r/20210716201039.3762203-1-guro@fb.com
Fixes: c22d70a162d3 ("writeback, cgroup: release dying cgwbs by switching attached inodes")
Signed-off-by: Roman Gushchin <guro@fb.com>
Reported-by: Boyang Xue <bxue@redhat.com>
Suggested-by: Jan Kara <jack@suse.cz>
Tested-by: Darrick J. Wong <djwong@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Murphy Zhou <jencce.kernel@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-23 17:43:28 -07:00
..
kasan
kasan: add memzero init for unaligned size at DEBUG
2021-07-15 10:13:49 -07:00
kfence
kfence: skip all GFP_ZONEMASK allocations
2021-07-23 17:43:28 -07:00
backing-dev.c
writeback, cgroup: remove wb from offline list before releasing refcnt
2021-07-23 17:43:28 -07:00
balloon_compaction.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
bootmem_info.c
mm: memory_hotplug: factor out bootmem core functions to bootmem_info.c
2021-06-30 20:47:25 -07:00
cleancache.c
…
cma_debug.c
mm/cma: change cma mutex to irq safe spinlock
2021-05-05 11:27:21 -07:00
cma_sysfs.c
mm: cma: support sysfs
2021-05-05 11:27:24 -07:00
cma.c
mm: use proper type for cma_[alloc|release]
2021-05-05 11:27:24 -07:00
cma.h
mm: cma: support sysfs
2021-05-05 11:27:24 -07:00
compaction.c
Merge branch 'akpm' (patches from Andrew)
2021-07-02 12:08:10 -07:00
debug_page_ref.c
…
debug_vm_pgtable.c
mm/swapops: rework swap entry manipulation code
2021-07-01 11:06:03 -07:00
debug.c
mm/debug: factor PagePoisoned out of __dump_page
2021-06-29 10:53:53 -07:00
dmapool.c
mm/dmapool: use DEVICE_ATTR_RO macro
2021-06-29 10:53:52 -07:00
early_ioremap.c
mm/early_ioremap.c: use __func__ instead of function name
2021-02-26 09:41:02 -08:00
fadvise.c
mm, fadvise: improve the expensive remote LRU cache draining after FADV_DONTNEED
2020-10-13 18:38:29 -07:00
failslab.c
…
filemap.c
Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2021-07-03 11:30:04 -07:00
frontswap.c
mm/mempool: minor coding style tweaks
2021-05-05 11:27:27 -07:00
gup_test.c
selftests/vm: gup_test: test faulting in kernel, and verify pinnable pages
2021-05-05 11:27:26 -07:00
gup_test.h
selftests/vm: gup_test: fix test flag
2021-05-05 11:27:26 -07:00
gup.c
mm: introduce memfd_secret system call to create "secret" memory areas
2021-07-08 11:48:21 -07:00
highmem.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
hmm.c
mm: device exclusive memory access
2021-07-01 11:06:03 -07:00
huge_memory.c
mm/rmap: fix comments left over from recent changes
2021-07-11 15:05:15 -07:00
hugetlb_cgroup.c
hugetlb: make free_huge_page irq safe
2021-05-05 11:27:22 -07:00
hugetlb_vmemmap.c
mm: hugetlb: introduce CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON
2021-06-30 20:47:26 -07:00
hugetlb_vmemmap.h
mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate
2021-06-30 20:47:25 -07:00
hugetlb.c
mm/hugetlb: fix refs calculation from unaligned @vaddr
2021-07-15 10:13:49 -07:00
hwpoison-inject.c
mm,hwpoison-inject: don't pin for hwpoison_filter
2020-10-16 11:11:16 -07:00
init-mm.c
mm: add setup_initial_init_mm() helper
2021-07-08 11:48:21 -07:00
internal.h
mmap: make mlock_future_check() global
2021-07-08 11:48:20 -07:00
interval_tree.c
mm/interval_tree: add comments to improve code readability
2021-04-30 11:20:38 -07:00
io-mapping.c
mm: add a io_mapping_map_user helper
2021-04-30 11:20:39 -07:00
ioremap.c
mm/ioremap: fix iomap_max_page_shift
2021-05-14 19:41:32 -07:00
Kconfig
mm: introduce memfd_secret system call to create "secret" memory areas
2021-07-08 11:48:21 -07:00
Kconfig.debug
mm, page_poison: remove CONFIG_PAGE_POISONING_ZERO
2020-12-15 12:13:46 -08:00
khugepaged.c
mm, thp: relax the VM_DENYWRITE constraint on file-backed THPs
2021-06-30 20:47:29 -07:00
kmemleak.c
mm/kmemleak: fix possible wrong memory scanning period
2021-06-29 10:53:47 -07:00
ksm.c
mm/ksm: use vma_lookup() in find_mergeable_vma()
2021-06-29 10:53:52 -07:00
list_lru.c
mm: vmscan: consolidate shrinker_maps handling code
2021-05-05 11:27:23 -07:00
maccess.c
uaccess: add force_uaccess_{begin,end} helpers
2020-08-12 10:57:59 -07:00
madvise.c
mm/madvise: introduce MADV_POPULATE_(READ|WRITE) to prefault page tables
2021-06-30 20:47:30 -07:00
Makefile
mm: introduce memfd_secret system call to create "secret" memory areas
2021-07-08 11:48:21 -07:00
mapping_dirty_helpers.c
mm/mapping_dirty_helpers: remove double Note in kerneldoc
2021-07-01 11:06:02 -07:00
memblock.c
memblock: make for_each_mem_range() traverse MEMBLOCK_HOTPLUG regions
2021-07-23 17:43:28 -07:00
memcontrol.c
Merge branch 'akpm' (patches from Andrew)
2021-07-02 12:08:10 -07:00
memfd.c
Reimplement RLIMIT_MEMLOCK on top of ucounts
2021-04-30 14:14:02 -05:00
memory_hotplug.c
mm/memory_hotplug: fix kerneldoc comment for __remove_memory
2021-07-01 11:06:02 -07:00
memory-failure.c
mm: fix spelling mistakes
2021-07-01 11:06:02 -07:00
memory.c
mm: device exclusive memory access
2021-07-01 11:06:03 -07:00
mempolicy.c
mm/mempolicy: use unified 'nodes' for bind/interleave/prefer policies
2021-06-30 20:47:29 -07:00
mempool.c
kasan: use separate (un)poison implementation for integrated init
2021-06-04 19:32:21 +01:00
memremap.c
mm/memremap.c: fix improper SPDX comment style
2021-04-30 11:20:37 -07:00
memtest.c
…
migrate.c
mm: Make copy_huge_page() always available
2021-07-12 11:30:56 -07:00
mincore.c
inode: make init and permission helpers idmapped mount aware
2021-01-24 14:27:16 +01:00
mlock.c
mm: introduce memfd_secret system call to create "secret" memory areas
2021-07-08 11:48:21 -07:00
mm_init.c
include/linux/page-flags-layout.h: cleanups
2021-04-30 11:20:42 -07:00
mmap_lock.c
mm/mmap_lock: remove dead code for !CONFIG_TRACING configurations
2021-07-01 11:06:03 -07:00
mmap.c
mmap: make mlock_future_check() global
2021-07-08 11:48:20 -07:00
mmu_gather.c
mm: eliminate "expecting prototype" kernel-doc warnings
2021-04-16 16:10:36 -07:00
mmu_notifier.c
mm/mmu_notifiers: ensure range_end() is paired with range_start()
2021-03-25 09:22:55 -07:00
mmzone.c
mm/lru: replace pgdat lru_lock with lruvec lock
2020-12-15 14:48:04 -08:00
mprotect.c
mm: device exclusive memory access
2021-07-01 11:06:03 -07:00
mremap.c
mm/mremap: allow arch runtime override
2021-07-08 11:48:23 -07:00
msync.c
mm/msync: exit early when the flags is an MS_ASYNC and start < vm_start
2021-04-30 11:20:37 -07:00
nommu.c
mm/nommu: unexport do_munmap()
2021-06-30 20:47:30 -07:00
oom_kill.c
Merge branch 'core-rcu-2021.07.04' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
2021-07-04 12:58:33 -07:00
page_alloc.c
mm: page_alloc: fix page_poison=1 / INIT_ON_ALLOC_DEFAULT_ON interaction
2021-07-23 17:43:28 -07:00
page_counter.c
mm: page_counter: mitigate consequences of a page_counter underflow
2021-04-30 11:20:38 -07:00
page_ext.c
mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
2021-06-29 10:53:55 -07:00
page_idle.c
mm: page_idle_get_page() does not need lru_lock
2020-12-15 14:48:03 -08:00
page_io.c
swap: fix swapfile read/write offset
2021-03-02 17:25:46 -07:00
page_isolation.c
mm/page_isolation: do not isolate the max order page
2020-12-15 12:13:45 -08:00
page_owner.c
mm/page_owner: constify dump_page_owner
2021-06-29 10:53:53 -07:00
page_poison.c
mm: page_poison: print page info when corruption is caught
2021-04-30 11:20:36 -07:00
page_reporting.c
mm/page_reporting: allow driver to specify reporting order
2021-06-29 10:53:47 -07:00
page_reporting.h
mm/page_reporting: export reporting order as module parameter
2021-06-29 10:53:47 -07:00
page_vma_mapped.c
mm: device exclusive memory access
2021-07-01 11:06:03 -07:00
page-writeback.c
for-5.14/block-2021-06-29
2021-06-30 12:12:56 -07:00
pagewalk.c
mm: pagewalk: fix walk for hugepage tables
2021-06-29 10:53:49 -07:00
percpu-internal.h
Merge branch 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu
2021-07-01 17:17:24 -07:00
percpu-km.c
percpu: flush tlb in pcpu_reclaim_populated()
2021-07-04 18:30:17 +00:00
percpu-stats.c
percpu: rework memcg accounting
2021-06-05 20:43:15 +00:00
percpu-vm.c
percpu: flush tlb in pcpu_reclaim_populated()
2021-07-04 18:30:17 +00:00
percpu.c
percpu: flush tlb in pcpu_reclaim_populated()
2021-07-04 18:30:17 +00:00
pgalloc-track.h
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
pgtable-generic.c
mm/thp: fix __split_huge_pmd_locked() on shmem migration entry
2021-06-16 09:24:42 -07:00
process_vm_access.c
mm/process_vm_access.c: remove duplicate include
2021-05-05 11:27:27 -07:00
ptdump.c
mm: ptdump: fix build failure
2021-04-16 16:10:37 -07:00
readahead.c
mm: Implement readahead_control pageset expansion
2021-04-23 10:14:29 +01:00
rmap.c
mm/rmap: fix munlocking Anon THP with mlocked ptes
2021-07-12 11:30:56 -07:00
rodata_test.c
mm/rodata_test.c: fix missing function declaration
2020-08-21 09:52:53 -07:00
secretmem.c
PM: hibernate: disable when there are active secretmem users
2021-07-08 11:48:21 -07:00
shmem.c
Merge branch 'akpm' (patches from Andrew)
2021-07-02 12:08:10 -07:00
shuffle.c
mm: eliminate "expecting prototype" kernel-doc warnings
2021-04-16 16:10:36 -07:00
shuffle.h
mm/shuffle: fix section mismatch warning
2021-05-22 15:09:07 -10:00
slab_common.c
Merge branch 'core-rcu-2021.07.04' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
2021-07-04 12:58:33 -07:00
slab.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
slab.h
mm: move helper to check slub_debug_enabled
2021-07-15 10:13:49 -07:00
slob.c
mm: Don't build mm_dump_obj() on CONFIG_PRINTK=n kernels
2021-03-08 14:18:46 -08:00
slub.c
Revert "mm/slub: use stackdepot to save stack trace in objects"
2021-07-17 13:27:00 -07:00
sparse-vmemmap.c
mm: sparsemem: split the huge PMD mapping of vmemmap pages
2021-06-30 20:47:26 -07:00
sparse.c
mm: memory_hotplug: factor out bootmem core functions to bootmem_info.c
2021-06-30 20:47:25 -07:00
swap_cgroup.c
mm: memcontrol: make swap tracking an integral part of memory control
2020-06-03 20:09:48 -07:00
swap_slots.c
mm/swap_slots.c: delete meaningless forward declarations
2021-06-29 10:53:49 -07:00
swap_state.c
swap: check mapping_empty() for swap cache before being freed
2021-06-29 10:53:49 -07:00
swap.c
mm: fix typos and grammar error in comments
2021-07-01 11:06:02 -07:00
swapfile.c
mm: fix spelling mistakes
2021-07-01 11:06:02 -07:00
truncate.c
mm/thp: unmap_mapping_page() to fix THP truncate_cleanup_page()
2021-06-16 09:24:42 -07:00
usercopy.c
mm/usercopy.c: delete duplicated word
2020-08-12 10:57:58 -07:00
userfaultfd.c
userfaultfd/shmem: modify shmem_mfill_atomic_pte to use install_pte()
2021-06-30 20:47:27 -07:00
util.c
mm: Make copy_huge_page() always available
2021-07-12 11:30:56 -07:00
vmacache.c
kernel: better document the use_mm/unuse_mm API contract
2020-06-10 19:14:18 -07:00
vmalloc.c
mm/vmalloc: include header for prototype of set_iounmap_nonlazy
2021-07-01 11:06:02 -07:00
vmpressure.c
mm: vmpressure: use mem_cgroup_is_root API
2020-04-02 09:35:31 -07:00
vmscan.c
mm/vmscan: remove kerneldoc-like comment from isolate_lru_pages
2021-07-01 11:06:02 -07:00
vmstat.c
mm/vmstat: inline NUMA event counter updates
2021-06-29 10:53:54 -07:00
workingset.c
mm: workingset: define macro WORKINGSET_SHIFT
2021-06-30 20:47:28 -07:00
z3fold.c
mm/z3fold: add kerneldoc fields for z3fold_pool
2021-07-01 11:06:03 -07:00
zbud.c
mm/zbud: add kerneldoc fields for zbud_pool
2021-07-01 11:06:03 -07:00
zpool.c
mm: fix typos in comments
2021-05-07 00:26:35 -07:00
zsmalloc.c
mm/zsmalloc.c: improve readability for async_free_zspage()
2021-07-01 11:06:02 -07:00
zswap.c
mm/zswap.c: fix two bugs in zswap_writeback_entry()
2021-06-30 20:47:31 -07:00