syzbot


possible deadlock in page_cache_ra_unbounded (2)

Status: moderation: reported on 2025/04/17 16:05
Subsystems: mm fs
[Documentation on labels]
Reported-by: syzbot+dada432f42ae8bce1250@syzkaller.appspotmail.com
First crash: 55d, last: 16d
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in page_cache_ra_unbounded mm fs C error done 163 139d 900d 28/28 fixed on 2025/03/05 08:48

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc7-syzkaller-00082-g5cdb2c77c4c3 #0 Not tainted
------------------------------------------------------
syz.0.0/5334 is trying to acquire lock:
ffff8880441fef20 (mapping.invalidate_lock#3){.+.+}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:922 [inline]
ffff8880441fef20 (mapping.invalidate_lock#3){.+.+}-{4:4}, at: page_cache_ra_unbounded+0x129/0x7b0 mm/readahead.c:228

but task is already holding lock:
ffff8880119f95e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:203 [inline]
ffff8880119f95e0 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/memory.c:6346 [inline]
ffff8880119f95e0 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x32/0x300 mm/memory.c:6406

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&mm->mmap_lock){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       __might_fault+0xcc/0x130 mm/memory.c:7151
       _inline_copy_to_user include/linux/uaccess.h:192 [inline]
       _copy_to_user+0x2c/0xb0 lib/usercopy.c:26
       copy_to_user include/linux/uaccess.h:225 [inline]
       fiemap_fill_next_extent+0x1c0/0x390 fs/ioctl.c:145
       ocfs2_fiemap+0x888/0xc90 fs/ocfs2/extent_map.c:806
       ioctl_fiemap fs/ioctl.c:220 [inline]
       do_vfs_ioctl+0x163b/0x1eb0 fs/ioctl.c:840
       __do_sys_ioctl fs/ioctl.c:904 [inline]
       __se_sys_ioctl+0x82/0x170 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&oi->ip_alloc_sem){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524
       ocfs2_read_folio+0x353/0x970 fs/ocfs2/aops.c:287
       filemap_read_folio+0x117/0x380 mm/filemap.c:2401
       filemap_fault+0xb1a/0x1200 mm/filemap.c:3495
       ocfs2_fault+0xa4/0x3f0 fs/ocfs2/mmap.c:38
       __do_fault+0x135/0x390 mm/memory.c:5098
       do_shared_fault mm/memory.c:5582 [inline]
       do_fault mm/memory.c:5656 [inline]
       do_pte_missing mm/memory.c:4160 [inline]
       handle_pte_fault mm/memory.c:5997 [inline]
       __handle_mm_fault+0x17f9/0x5380 mm/memory.c:6140
       handle_mm_fault+0x3f6/0x8c0 mm/memory.c:6309
       do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1388
       handle_page_fault arch/x86/mm/fault.c:1480 [inline]
       exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #0 (mapping.invalidate_lock#3){.+.+}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3166 [inline]
       check_prevs_add kernel/locking/lockdep.c:3285 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909
       __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524
       filemap_invalidate_lock_shared include/linux/fs.h:922 [inline]
       page_cache_ra_unbounded+0x129/0x7b0 mm/readahead.c:228
       do_sync_mmap_readahead+0x4b5/0x5f0 mm/filemap.c:3262
       filemap_fault+0x62a/0x1200 mm/filemap.c:3403
       ocfs2_fault+0xa4/0x3f0 fs/ocfs2/mmap.c:38
       __do_fault+0x135/0x390 mm/memory.c:5098
       do_shared_fault mm/memory.c:5582 [inline]
       do_fault mm/memory.c:5656 [inline]
       do_pte_missing mm/memory.c:4160 [inline]
       handle_pte_fault mm/memory.c:5997 [inline]
       __handle_mm_fault+0x17f9/0x5380 mm/memory.c:6140
       handle_mm_fault+0x3f6/0x8c0 mm/memory.c:6309
       do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1388
       handle_page_fault arch/x86/mm/fault.c:1480 [inline]
       exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

other info that might help us debug this:

Chain exists of:
  mapping.invalidate_lock#3 --> &oi->ip_alloc_sem --> &mm->mmap_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&mm->mmap_lock);
                               lock(&oi->ip_alloc_sem);
                               lock(&mm->mmap_lock);
  rlock(mapping.invalidate_lock#3);

 *** DEADLOCK ***

1 lock held by syz.0.0/5334:
 #0: ffff8880119f95e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:203 [inline]
 #0: ffff8880119f95e0 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/memory.c:6346 [inline]
 #0: ffff8880119f95e0 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x32/0x300 mm/memory.c:6406

stack backtrace:
CPU: 0 UID: 0 PID: 5334 Comm: syz.0.0 Not tainted 6.15.0-rc7-syzkaller-00082-g5cdb2c77c4c3 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2079
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2211
 check_prev_add kernel/locking/lockdep.c:3166 [inline]
 check_prevs_add kernel/locking/lockdep.c:3285 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909
 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524
 filemap_invalidate_lock_shared include/linux/fs.h:922 [inline]
 page_cache_ra_unbounded+0x129/0x7b0 mm/readahead.c:228
 do_sync_mmap_readahead+0x4b5/0x5f0 mm/filemap.c:3262
 filemap_fault+0x62a/0x1200 mm/filemap.c:3403
 ocfs2_fault+0xa4/0x3f0 fs/ocfs2/mmap.c:38
 __do_fault+0x135/0x390 mm/memory.c:5098
 do_shared_fault mm/memory.c:5582 [inline]
 do_fault mm/memory.c:5656 [inline]
 do_pte_missing mm/memory.c:4160 [inline]
 handle_pte_fault mm/memory.c:5997 [inline]
 __handle_mm_fault+0x17f9/0x5380 mm/memory.c:6140
 handle_mm_fault+0x3f6/0x8c0 mm/memory.c:6309
 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1388
 handle_page_fault arch/x86/mm/fault.c:1480 [inline]
 exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0033:0x7f7cf9b57e48
Code: 66 89 74 17 02 88 0f c3 c5 fa 6f 06 c5 fa 6f 4c 16 f0 c5 fa 7f 07 c5 fa 7f 4c 17 f0 c3 0f 1f 44 00 00 48 8b 4c 16 f8 48 8b 36 <48> 89 37 48 89 4c 17 f8 c3 62 e1 fe 28 6f 54 16 ff 62 e1 fe 28 6f
RSP: 002b:00007ffd46703ad8 EFLAGS: 00010206
RAX: 0000200000000140 RBX: 0000000000000004 RCX: 0023706f6f6c2f76
RDX: 000000000000000b RSI: 6f6f6c2f7665642f RDI: 0000200000000140
RBP: 00007f7cf9db7ba0 R08: 00007f7cf99ff03c R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000009 R12: 00007f7cf9db5fac
R13: 00007ffd46703bd0 R14: fffffffffffffffe R15: 00007ffd46703bf0
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/23 01:06 upstream 5cdb2c77c4c3 fa44301a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in page_cache_ra_unbounded
2025/04/13 15:54 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 2fe2b96c3818 0bd6db41 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in page_cache_ra_unbounded
* Struck through repros no longer work on HEAD.