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: 33d, last: 33d
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 117d 877d 28/28 fixed on 2025/03/05 08:48

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc1-syzkaller-g2fe2b96c3818 #0 Not tainted
------------------------------------------------------
syz.1.367/8496 is trying to acquire lock:
ffff0000dde499a0 (mapping.invalidate_lock#7){.+.+}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:922 [inline]
ffff0000dde499a0 (mapping.invalidate_lock#7){.+.+}-{4:4}, at: page_cache_ra_unbounded+0x100/0x758 mm/readahead.c:228

but task is already holding lock:
ffff0000d4fc23d0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable include/linux/mmap_lock.h:193 [inline]
ffff0000d4fc23d0 (&mm->mmap_lock){++++}-{4:4}, at: __get_user_pages_locked mm/gup.c:1812 [inline]
ffff0000d4fc23d0 (&mm->mmap_lock){++++}-{4:4}, at: faultin_page_range+0x33c/0x778 mm/gup.c:1981

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&mm->mmap_lock){++++}-{4:4}:
       __might_fault+0xc4/0x124 mm/memory.c:7151
       _inline_copy_to_user include/linux/uaccess.h:192 [inline]
       copy_to_user include/linux/uaccess.h:223 [inline]
       fiemap_fill_next_extent+0x1d0/0x45c fs/ioctl.c:145
       ocfs2_fiemap+0x894/0xe04 fs/ocfs2/extent_map.c:806
       ioctl_fiemap fs/ioctl.c:220 [inline]
       do_vfs_ioctl+0x1b14/0x26f4 fs/ioctl.c:840
       __do_sys_ioctl fs/ioctl.c:904 [inline]
       __se_sys_ioctl fs/ioctl.c:892 [inline]
       __arm64_sys_ioctl+0xe4/0x1c4 fs/ioctl.c:892
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

-> #1 (&ocfs2_file_ip_alloc_sem_key){++++}-{4:4}:
       down_read+0x58/0x2fc kernel/locking/rwsem.c:1524
       ocfs2_read_folio+0x328/0x970 fs/ocfs2/aops.c:287
       filemap_read_folio+0x108/0x318 mm/filemap.c:2400
       filemap_fault+0xe24/0x1364 mm/filemap.c:3494
       ocfs2_fault+0xbc/0x494 fs/ocfs2/mmap.c:38
       __do_fault+0xf8/0x498 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+0x1320/0x5c94 mm/memory.c:5997
       __handle_mm_fault mm/memory.c:6140 [inline]
       handle_mm_fault+0xf18/0x17bc mm/memory.c:6309
       faultin_page mm/gup.c:1193 [inline]
       __get_user_pages+0x187c/0x3408 mm/gup.c:1491
       __get_user_pages_locked mm/gup.c:1757 [inline]
       faultin_page_range+0x200/0x778 mm/gup.c:1981
       madvise_populate mm/madvise.c:965 [inline]
       madvise_do_behavior+0x4bc/0x2fc0 mm/madvise.c:1693
       do_madvise mm/madvise.c:1782 [inline]
       __do_sys_madvise mm/madvise.c:1790 [inline]
       __se_sys_madvise mm/madvise.c:1788 [inline]
       __arm64_sys_madvise+0x164/0x1f8 mm/madvise.c:1788
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

-> #0 (mapping.invalidate_lock#7){.+.+}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3166 [inline]
       check_prevs_add kernel/locking/lockdep.c:3285 [inline]
       validate_chain kernel/locking/lockdep.c:3909 [inline]
       __lock_acquire+0x17b8/0x32c4 kernel/locking/lockdep.c:5235
       lock_acquire+0x150/0x2e8 kernel/locking/lockdep.c:5866
       down_read+0x58/0x2fc kernel/locking/rwsem.c:1524
       filemap_invalidate_lock_shared include/linux/fs.h:922 [inline]
       page_cache_ra_unbounded+0x100/0x758 mm/readahead.c:228
       do_page_cache_ra mm/readahead.c:327 [inline]
       page_cache_ra_order+0x960/0xb8c mm/readahead.c:532
       do_sync_mmap_readahead+0x3a8/0x834 mm/filemap.c:-1
       filemap_fault+0x68c/0x1364 mm/filemap.c:3402
       ocfs2_fault+0xbc/0x494 fs/ocfs2/mmap.c:38
       __do_fault+0xf8/0x498 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+0x1320/0x5c94 mm/memory.c:5997
       __handle_mm_fault mm/memory.c:6140 [inline]
       handle_mm_fault+0xf18/0x17bc mm/memory.c:6309
       faultin_page mm/gup.c:1193 [inline]
       __get_user_pages+0x187c/0x3408 mm/gup.c:1491
       __get_user_pages_locked mm/gup.c:1821 [inline]
       faultin_page_range+0x384/0x778 mm/gup.c:1981
       madvise_populate mm/madvise.c:965 [inline]
       madvise_do_behavior+0x4bc/0x2fc0 mm/madvise.c:1693
       do_madvise mm/madvise.c:1782 [inline]
       __do_sys_madvise mm/madvise.c:1790 [inline]
       __se_sys_madvise mm/madvise.c:1788 [inline]
       __arm64_sys_madvise+0x164/0x1f8 mm/madvise.c:1788
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

other info that might help us debug this:

Chain exists of:
  mapping.invalidate_lock#7 --> &ocfs2_file_ip_alloc_sem_key --> &mm->mmap_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&mm->mmap_lock);
                               lock(&ocfs2_file_ip_alloc_sem_key);
                               lock(&mm->mmap_lock);
  rlock(mapping.invalidate_lock#7);

 *** DEADLOCK ***

1 lock held by syz.1.367/8496:
 #0: ffff0000d4fc23d0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable include/linux/mmap_lock.h:193 [inline]
 #0: ffff0000d4fc23d0 (&mm->mmap_lock){++++}-{4:4}, at: __get_user_pages_locked mm/gup.c:1812 [inline]
 #0: ffff0000d4fc23d0 (&mm->mmap_lock){++++}-{4:4}, at: faultin_page_range+0x33c/0x778 mm/gup.c:1981

stack backtrace:
CPU: 1 UID: 0 PID: 8496 Comm: syz.1.367 Not tainted 6.15.0-rc1-syzkaller-g2fe2b96c3818 #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_circular_bug+0x32c/0x334 kernel/locking/lockdep.c:2079
 check_noncircular+0x15c/0x178 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 kernel/locking/lockdep.c:3909 [inline]
 __lock_acquire+0x17b8/0x32c4 kernel/locking/lockdep.c:5235
 lock_acquire+0x150/0x2e8 kernel/locking/lockdep.c:5866
 down_read+0x58/0x2fc kernel/locking/rwsem.c:1524
 filemap_invalidate_lock_shared include/linux/fs.h:922 [inline]
 page_cache_ra_unbounded+0x100/0x758 mm/readahead.c:228
 do_page_cache_ra mm/readahead.c:327 [inline]
 page_cache_ra_order+0x960/0xb8c mm/readahead.c:532
 do_sync_mmap_readahead+0x3a8/0x834 mm/filemap.c:-1
 filemap_fault+0x68c/0x1364 mm/filemap.c:3402
 ocfs2_fault+0xbc/0x494 fs/ocfs2/mmap.c:38
 __do_fault+0xf8/0x498 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+0x1320/0x5c94 mm/memory.c:5997
 __handle_mm_fault mm/memory.c:6140 [inline]
 handle_mm_fault+0xf18/0x17bc mm/memory.c:6309
 faultin_page mm/gup.c:1193 [inline]
 __get_user_pages+0x187c/0x3408 mm/gup.c:1491
 __get_user_pages_locked mm/gup.c:1821 [inline]
 faultin_page_range+0x384/0x778 mm/gup.c:1981
 madvise_populate mm/madvise.c:965 [inline]
 madvise_do_behavior+0x4bc/0x2fc0 mm/madvise.c:1693
 do_madvise mm/madvise.c:1782 [inline]
 __do_sys_madvise mm/madvise.c:1790 [inline]
 __se_sys_madvise mm/madvise.c:1788 [inline]
 __arm64_sys_madvise+0x164/0x1f8 mm/madvise.c:1788
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.