Re: [syzbot] INFO: task can't die in reclaim_throttle

[Vlastimil Babka <vbabka@suse.cz>]

On 12/9/21 01:52, syzbot wrote:
> Hello,

+ CC Mel

> syzbot found the following issue on:
> 
> HEAD commit:    4eee8d0b64ec Add linux-next specific files for 20211208
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=113d8d75b00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=20b74d9da4ce1ef1
> dashboard link: https://syzkaller.appspot.com/bug?extid=dcea9eda277e1090b35f
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+dcea9eda277e1090b35f@syzkaller.appspotmail.com
> 
> INFO: task syz-executor.5:925 can't die for more than 143 seconds.
> task:syz-executor.5  state:D
>  stack:23840 pid:  925 ppid:   565 flags:0x00004006
> Call Trace:
>  <TASK>
>  context_switch kernel/sched/core.c:4986 [inline]
>  __schedule+0xab2/0x4d90 kernel/sched/core.c:6296
>  schedule+0xd2/0x260 kernel/sched/core.c:6369
>  schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881
>  reclaim_throttle+0x1ce/0x5e0 mm/vmscan.c:1072
>  consider_reclaim_throttle mm/vmscan.c:3399 [inline]
>  shrink_zones mm/vmscan.c:3486 [inline]
>  do_try_to_free_pages+0x7cd/0x1620 mm/vmscan.c:3541
>  try_to_free_pages+0x29f/0x750 mm/vmscan.c:3776
>  __perform_reclaim mm/page_alloc.c:4603 [inline]
>  __alloc_pages_direct_reclaim mm/page_alloc.c:4624 [inline]
>  __alloc_pages_slowpath.constprop.0+0xa9e/0x2080 mm/page_alloc.c:5014
>  __alloc_pages+0x412/0x500 mm/page_alloc.c:5389
>  alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271
>  alloc_slab_page mm/slub.c:1799 [inline]
>  allocate_slab mm/slub.c:1952 [inline]
>  new_slab+0x2a9/0x3a0 mm/slub.c:2004
>  ___slab_alloc+0x6be/0xd60 mm/slub.c:3019
>  __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3106
>  slab_alloc_node mm/slub.c:3197 [inline]
>  slab_alloc mm/slub.c:3239 [inline]
>  kmem_cache_alloc+0x35c/0x3a0 mm/slub.c:3244
>  mempool_alloc+0x146/0x350 mm/mempool.c:392
>  bvec_alloc+0x16b/0x200 block/bio.c:206
>  bio_alloc_bioset+0x376/0x4a0 block/bio.c:481
>  bio_alloc include/linux/bio.h:371 [inline]
>  mpage_alloc+0x2f/0x1b0 fs/mpage.c:79
>  do_mpage_readpage+0xfa9/0x2590 fs/mpage.c:306
>  mpage_readahead+0x3db/0x920 fs/mpage.c:389
>  read_pages+0x1db/0x790 mm/readahead.c:129
>  page_cache_ra_unbounded+0x585/0x780 mm/readahead.c:238
>  do_page_cache_ra+0xf9/0x140 mm/readahead.c:268
>  do_sync_mmap_readahead mm/filemap.c:3058 [inline]
>  filemap_fault+0x157f/0x21c0 mm/filemap.c:3151
>  __do_fault+0x10d/0x790 mm/memory.c:3846
>  do_read_fault mm/memory.c:4161 [inline]
>  do_fault mm/memory.c:4290 [inline]
>  handle_pte_fault mm/memory.c:4548 [inline]
>  __handle_mm_fault+0x2761/0x4160 mm/memory.c:4683
>  handle_mm_fault+0x1c8/0x790 mm/memory.c:4781
>  faultin_page mm/gup.c:939 [inline]
>  __get_user_pages+0x503/0xf80 mm/gup.c:1160
>  populate_vma_page_range+0x24d/0x330 mm/gup.c:1492
>  __mm_populate+0x1ea/0x3e0 mm/gup.c:1601
>  mm_populate include/linux/mm.h:2698 [inline]
>  vm_mmap_pgoff+0x20e/0x290 mm/util.c:524
>  ksys_mmap_pgoff+0x40d/0x5a0 mm/mmap.c:1630
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7fd1c83f6af9
> RSP: 002b:00007fd1c736c188 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
> RAX: ffffffffffffffda RBX: 00007fd1c8509f60 RCX: 00007fd1c83f6af9
> RDX: 0000000001000002 RSI: 0000000000b36000 RDI: 0000000020000000
> RBP: 00007fd1c8450ff7 R08: 0000000000000004 R09: 0000000000000000
> R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007fff309a431f R14: 00007fd1c736c300 R15: 0000000000022000
>  </TASK>
> 
> Showing all locks held in the system:
> 1 lock held by khungtaskd/26:
>  #0: ffffffff8bb828a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6460
> 1 lock held by kswapd1/99:
> 1 lock held by in:imklog/6230:
>  #0: ffff888021d92370 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:994
> 1 lock held by syz-executor.5/925:
> 
> =============================================
> 
> 
> 
> ---
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