syzbot


possible deadlock in page_cache_ra_unbounded (2)

Status: moderation: reported on 2025/04/17 16:05
Subsystems: fs mm
[Documentation on labels]
Reported-by: syzbot+dada432f42ae8bce1250@syzkaller.appspotmail.com
First crash: 90d, last: 10d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in page_cache_ra_unbounded mm fs 4 C error done 163 173d 934d 28/29 fixed on 2025/03/05 08:48

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.16.0-rc4-syzkaller-00013-g66701750d556 #0 Not tainted
------------------------------------------------------
syz.3.104/6783 is trying to acquire lock:
ffff888053e5e0e0 (mapping.invalidate_lock#8){.+.+}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:934 [inline]
ffff888053e5e0e0 (mapping.invalidate_lock#8){.+.+}-{4:4}, at: page_cache_ra_unbounded+0x129/0x7b0 mm/readahead.c:228

but task is already holding lock:
ffff8880227a7560 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable include/linux/mmap_lock.h:421 [inline]
ffff8880227a7560 (&mm->mmap_lock){++++}-{4:4}, at: __get_user_pages_locked mm/gup.c:1809 [inline]
ffff8880227a7560 (&mm->mmap_lock){++++}-{4:4}, at: __gup_longterm_locked+0x1005/0x15b0 mm/gup.c:2512

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:5871
       __might_fault+0xcc/0x130 mm/memory.c:6971
       _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+0x16d3/0x1990 fs/ioctl.c:841
       __do_sys_ioctl fs/ioctl.c:905 [inline]
       __se_sys_ioctl+0x82/0x170 fs/ioctl.c:893
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 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:5871
       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:2412
       filemap_fault+0xb16/0x1200 mm/filemap.c:3504
       ocfs2_fault+0xa4/0x3f0 fs/ocfs2/mmap.c:38
       __do_fault+0x135/0x390 mm/memory.c:5169
       do_shared_fault mm/memory.c:5654 [inline]
       do_fault mm/memory.c:5728 [inline]
       do_pte_missing mm/memory.c:4251 [inline]
       handle_pte_fault mm/memory.c:6069 [inline]
       __handle_mm_fault+0x198b/0x5620 mm/memory.c:6212
       handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381
       faultin_page mm/gup.c:1186 [inline]
       __get_user_pages+0x1af4/0x30b0 mm/gup.c:1488
       __get_user_pages_locked mm/gup.c:1754 [inline]
       __gup_longterm_locked+0xd66/0x15b0 mm/gup.c:2512
       gup_fast_fallback+0x1cd4/0x2260 mm/gup.c:3363
       iov_iter_extract_user_pages lib/iov_iter.c:1846 [inline]
       iov_iter_extract_pages+0x35a/0x5e0 lib/iov_iter.c:1909
       dio_refill_pages fs/direct-io.c:172 [inline]
       dio_get_page fs/direct-io.c:213 [inline]
       do_direct_IO fs/direct-io.c:915 [inline]
       __blockdev_direct_IO+0x114f/0x33d0 fs/direct-io.c:1243
       ocfs2_direct_IO+0x25f/0x2d0 fs/ocfs2/aops.c:2438
       generic_file_read_iter+0x31c/0x510 mm/filemap.c:2880
       ocfs2_file_read_iter+0x3fa/0xa80 fs/ocfs2/file.c:2589
       new_sync_read fs/read_write.c:491 [inline]
       vfs_read+0x4cd/0x980 fs/read_write.c:572
       ksys_read+0x145/0x250 fs/read_write.c:715
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (mapping.invalidate_lock#8){.+.+}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3168 [inline]
       check_prevs_add kernel/locking/lockdep.c:3287 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524
       filemap_invalidate_lock_shared include/linux/fs.h:934 [inline]
       page_cache_ra_unbounded+0x129/0x7b0 mm/readahead.c:228
       do_sync_mmap_readahead+0x4b5/0x5f0 mm/filemap.c:3271
       filemap_fault+0x62a/0x1200 mm/filemap.c:3412
       ocfs2_fault+0xa4/0x3f0 fs/ocfs2/mmap.c:38
       __do_fault+0x135/0x390 mm/memory.c:5169
       do_shared_fault mm/memory.c:5654 [inline]
       do_fault mm/memory.c:5728 [inline]
       do_pte_missing mm/memory.c:4251 [inline]
       handle_pte_fault mm/memory.c:6069 [inline]
       __handle_mm_fault+0x198b/0x5620 mm/memory.c:6212
       handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381
       faultin_page mm/gup.c:1186 [inline]
       __get_user_pages+0x1af4/0x30b0 mm/gup.c:1488
       __get_user_pages_locked mm/gup.c:1818 [inline]
       __gup_longterm_locked+0x105d/0x15b0 mm/gup.c:2512
       gup_fast_fallback+0x1cd4/0x2260 mm/gup.c:3363
       iov_iter_extract_user_pages lib/iov_iter.c:1846 [inline]
       iov_iter_extract_pages+0x35a/0x5e0 lib/iov_iter.c:1909
       dio_refill_pages fs/direct-io.c:172 [inline]
       dio_get_page fs/direct-io.c:213 [inline]
       do_direct_IO fs/direct-io.c:915 [inline]
       __blockdev_direct_IO+0x114f/0x33d0 fs/direct-io.c:1243
       ocfs2_direct_IO+0x25f/0x2d0 fs/ocfs2/aops.c:2438
       generic_file_read_iter+0x31c/0x510 mm/filemap.c:2880
       ocfs2_file_read_iter+0x3fa/0xa80 fs/ocfs2/file.c:2589
       new_sync_read fs/read_write.c:491 [inline]
       vfs_read+0x4cd/0x980 fs/read_write.c:572
       ksys_read+0x145/0x250 fs/read_write.c:715
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  mapping.invalidate_lock#8 --> &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#8);

 *** DEADLOCK ***

2 locks held by syz.3.104/6783:
 #0: ffff8880344db5f8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x320 fs/file.c:1217
 #1: ffff8880227a7560 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable include/linux/mmap_lock.h:421 [inline]
 #1: ffff8880227a7560 (&mm->mmap_lock){++++}-{4:4}, at: __get_user_pages_locked mm/gup.c:1809 [inline]
 #1: ffff8880227a7560 (&mm->mmap_lock){++++}-{4:4}, at: __gup_longterm_locked+0x1005/0x15b0 mm/gup.c:2512

stack backtrace:
CPU: 0 UID: 0 PID: 6783 Comm: syz.3.104 Not tainted 6.16.0-rc4-syzkaller-00013-g66701750d556 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2046
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3168 [inline]
 check_prevs_add kernel/locking/lockdep.c:3287 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524
 filemap_invalidate_lock_shared include/linux/fs.h:934 [inline]
 page_cache_ra_unbounded+0x129/0x7b0 mm/readahead.c:228
 do_sync_mmap_readahead+0x4b5/0x5f0 mm/filemap.c:3271
 filemap_fault+0x62a/0x1200 mm/filemap.c:3412
 ocfs2_fault+0xa4/0x3f0 fs/ocfs2/mmap.c:38
 __do_fault+0x135/0x390 mm/memory.c:5169
 do_shared_fault mm/memory.c:5654 [inline]
 do_fault mm/memory.c:5728 [inline]
 do_pte_missing mm/memory.c:4251 [inline]
 handle_pte_fault mm/memory.c:6069 [inline]
 __handle_mm_fault+0x198b/0x5620 mm/memory.c:6212
 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381
 faultin_page mm/gup.c:1186 [inline]
 __get_user_pages+0x1af4/0x30b0 mm/gup.c:1488
 __get_user_pages_locked mm/gup.c:1818 [inline]
 __gup_longterm_locked+0x105d/0x15b0 mm/gup.c:2512
 gup_fast_fallback+0x1cd4/0x2260 mm/gup.c:3363
 iov_iter_extract_user_pages lib/iov_iter.c:1846 [inline]
 iov_iter_extract_pages+0x35a/0x5e0 lib/iov_iter.c:1909
 dio_refill_pages fs/direct-io.c:172 [inline]
 dio_get_page fs/direct-io.c:213 [inline]
 do_direct_IO fs/direct-io.c:915 [inline]
 __blockdev_direct_IO+0x114f/0x33d0 fs/direct-io.c:1243
 ocfs2_direct_IO+0x25f/0x2d0 fs/ocfs2/aops.c:2438
 generic_file_read_iter+0x31c/0x510 mm/filemap.c:2880
 ocfs2_file_read_iter+0x3fa/0xa80 fs/ocfs2/file.c:2589
 new_sync_read fs/read_write.c:491 [inline]
 vfs_read+0x4cd/0x980 fs/read_write.c:572
 ksys_read+0x145/0x250 fs/read_write.c:715
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe68598e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe6867aa038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fe685bb6080 RCX: 00007fe68598e929
RDX: 0000000000001000 RSI: 0000200000001400 RDI: 0000000000000004
RBP: 00007fe685a10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe685bb6080 R15: 00007ffc7777d898
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/02 02:53 upstream 66701750d556 091a06cd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in page_cache_ra_unbounded
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.