syzbot


possible deadlock in ext4_readpage_inline (2)

Status: upstream: reported on 2025/08/08 18:02
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+8721ec072bbbb6adcb01@syzkaller.appspotmail.com
First crash: 7d16h, last: 7d16h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] possible deadlock in ext4_readpage_inline (2) 0 (1) 2025/08/08 18:02
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in ext4_readpage_inline 4 1 304d 304d 0/3 auto-obsoleted due to no activity on 2025/01/19 18:46
upstream possible deadlock in ext4_readpage_inline ext4 4 6 204d 230d 0/29 auto-obsoleted due to no activity on 2025/04/29 21:42

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.16.0-syzkaller-11489-gd2eedaa3909b #0 Not tainted
------------------------------------------------------
syz.9.1907/11934 is trying to acquire lock:
ffff8880543c80c8 (&ei->xattr_sem){++++}-{4:4}, at: ext4_readpage_inline+0x36/0x6a0 fs/ext4/inline.c:531

but task is already holding lock:
ffff8880543c8580 (mapping.invalidate_lock#2){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:934 [inline]
ffff8880543c8580 (mapping.invalidate_lock#2){++++}-{4:4}, at: filemap_create_folio mm/filemap.c:2539 [inline]
ffff8880543c8580 (mapping.invalidate_lock#2){++++}-{4:4}, at: filemap_get_pages+0xc29/0x1ea0 mm/filemap.c:2609

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (mapping.invalidate_lock#2){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1537
       filemap_invalidate_lock_shared include/linux/fs.h:934 [inline]
       page_cache_ra_unbounded+0x129/0x7b0 mm/readahead.c:228
       do_async_mmap_readahead mm/filemap.c:3332 [inline]
       filemap_fault+0x5a0/0x1200 mm/filemap.c:3431
       __do_fault+0x138/0x390 mm/memory.c:5152
       do_read_fault mm/memory.c:5573 [inline]
       do_fault mm/memory.c:5707 [inline]
       do_pte_missing mm/memory.c:4234 [inline]
       handle_pte_fault mm/memory.c:6052 [inline]
       __handle_mm_fault+0x3611/0x5440 mm/memory.c:6195
       handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
       faultin_page mm/gup.c:1144 [inline]
       __get_user_pages+0x1699/0x2ce0 mm/gup.c:1446
       __get_user_pages_locked mm/gup.c:1712 [inline]
       get_dump_page+0x1ac/0x3f0 mm/gup.c:2212
       dump_user_range+0x1de/0xc90 fs/coredump.c:1364
       elf_core_dump+0x337b/0x3990 fs/binfmt_elf.c:2085
       coredump_write+0x1169/0x1900 fs/coredump.c:1049
       vfs_coredump+0x1a4b/0x2ab0 fs/coredump.c:1168
       get_signal+0x1109/0x1340 kernel/signal.c:3019
       arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
       exit_to_user_mode_loop kernel/entry/common.c:40 [inline]
       exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
       irqentry_exit_to_user_mode+0x81/0x120 kernel/entry/common.c:73
       exc_page_fault+0x9f/0xf0 arch/x86/mm/fault.c:1535
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #3 (&mm->mmap_lock){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __might_fault+0xcc/0x130 mm/memory.c:6958
       _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+0x1173/0x1430 fs/ioctl.c:532
       __do_sys_ioctl fs/ioctl.c:596 [inline]
       __se_sys_ioctl+0x82/0x170 fs/ioctl.c:584
       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

-> #2 (&ocfs2_quota_ip_alloc_sem_key){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
       ocfs2_create_local_dquot+0x19d/0x1a40 fs/ocfs2/quota_local.c:1227
       ocfs2_acquire_dquot+0x80f/0xb30 fs/ocfs2/quota_global.c:883
       dqget+0x7b1/0xf10 fs/quota/dquot.c:977
       ocfs2_setattr+0xd72/0x1b40 fs/ocfs2/file.c:1233
       notify_change+0xb36/0xe40 fs/attr.c:552
       chown_common+0x40c/0x5c0 fs/open.c:791
       vfs_fchown fs/open.c:859 [inline]
       ksys_fchown+0xea/0x160 fs/open.c:871
       __do_sys_fchown fs/open.c:876 [inline]
       __se_sys_fchown fs/open.c:874 [inline]
       __x64_sys_fchown+0x7a/0x90 fs/open.c:874
       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 (&dquot->dq_lock){+.+.}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x187/0x1360 kernel/locking/mutex.c:760
       wait_on_dquot fs/quota/dquot.c:354 [inline]
       dqget+0x72a/0xf10 fs/quota/dquot.c:972
       dquot_transfer+0x4b8/0x6d0 fs/quota/dquot.c:2154
       ext4_setattr+0x865/0x1bc0 fs/ext4/inode.c:5902
       notify_change+0xb36/0xe40 fs/attr.c:552
       ovl_do_notify_change fs/overlayfs/overlayfs.h:203 [inline]
       ovl_setattr+0x3a3/0x550 fs/overlayfs/inode.c:82
       notify_change+0xb36/0xe40 fs/attr.c:552
       chown_common+0x40c/0x5c0 fs/open.c:791
       do_fchownat+0x161/0x270 fs/open.c:822
       __do_sys_chown fs/open.c:842 [inline]
       __se_sys_chown fs/open.c:840 [inline]
       __x64_sys_chown+0x82/0xa0 fs/open.c:840
       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 (&ei->xattr_sem){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1537
       ext4_readpage_inline+0x36/0x6a0 fs/ext4/inline.c:531
       ext4_read_folio+0x16c/0x320 fs/ext4/inode.c:3390
       filemap_read_folio+0x117/0x380 mm/filemap.c:2413
       filemap_create_folio mm/filemap.c:2548 [inline]
       filemap_get_pages+0xd4e/0x1ea0 mm/filemap.c:2609
       filemap_read+0x3f6/0x11a0 mm/filemap.c:2712
       __kernel_read+0x46c/0x8c0 fs/read_write.c:530
       integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
       ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:480 [inline]
       ima_calc_file_shash security/integrity/ima/ima_crypto.c:511 [inline]
       ima_calc_file_hash+0x85e/0x16f0 security/integrity/ima/ima_crypto.c:568
       ima_collect_measurement+0x428/0x8e0 security/integrity/ima/ima_api.c:293
       process_measurement+0x1121/0x1a40 security/integrity/ima/ima_main.c:405
       ima_file_check+0xd7/0x120 security/integrity/ima/ima_main.c:633
       security_file_post_open+0xbb/0x290 security/security.c:3160
       do_open fs/namei.c:3889 [inline]
       path_openat+0x2f26/0x3830 fs/namei.c:4046
       do_filp_open+0x1fa/0x410 fs/namei.c:4073
       do_sys_openat2+0x121/0x1c0 fs/open.c:1435
       do_sys_open fs/open.c:1450 [inline]
       __do_sys_openat fs/open.c:1466 [inline]
       __se_sys_openat fs/open.c:1461 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1461
       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:
  &ei->xattr_sem --> &mm->mmap_lock --> mapping.invalidate_lock#2

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(mapping.invalidate_lock#2);
                               lock(&mm->mmap_lock);
                               lock(mapping.invalidate_lock#2);
  rlock(&ei->xattr_sem);

 *** DEADLOCK ***

3 locks held by syz.9.1907/11934:
 #0: ffff88805ebb2428 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:557
 #1: ffff88804df9d398 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: process_measurement+0x74b/0x1a40 security/integrity/ima/ima_main.c:299
 #2: ffff8880543c8580 (mapping.invalidate_lock#2){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:934 [inline]
 #2: ffff8880543c8580 (mapping.invalidate_lock#2){++++}-{4:4}, at: filemap_create_folio mm/filemap.c:2539 [inline]
 #2: ffff8880543c8580 (mapping.invalidate_lock#2){++++}-{4:4}, at: filemap_get_pages+0xc29/0x1ea0 mm/filemap.c:2609

stack backtrace:
CPU: 1 UID: 0 PID: 11934 Comm: syz.9.1907 Not tainted 6.16.0-syzkaller-11489-gd2eedaa3909b #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1537
 ext4_readpage_inline+0x36/0x6a0 fs/ext4/inline.c:531
 ext4_read_folio+0x16c/0x320 fs/ext4/inode.c:3390
 filemap_read_folio+0x117/0x380 mm/filemap.c:2413
 filemap_create_folio mm/filemap.c:2548 [inline]
 filemap_get_pages+0xd4e/0x1ea0 mm/filemap.c:2609
 filemap_read+0x3f6/0x11a0 mm/filemap.c:2712
 __kernel_read+0x46c/0x8c0 fs/read_write.c:530
 integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:480 [inline]
 ima_calc_file_shash security/integrity/ima/ima_crypto.c:511 [inline]
 ima_calc_file_hash+0x85e/0x16f0 security/integrity/ima/ima_crypto.c:568
 ima_collect_measurement+0x428/0x8e0 security/integrity/ima/ima_api.c:293
 process_measurement+0x1121/0x1a40 security/integrity/ima/ima_main.c:405
 ima_file_check+0xd7/0x120 security/integrity/ima/ima_main.c:633
 security_file_post_open+0xbb/0x290 security/security.c:3160
 do_open fs/namei.c:3889 [inline]
 path_openat+0x2f26/0x3830 fs/namei.c:4046
 do_filp_open+0x1fa/0x410 fs/namei.c:4073
 do_sys_openat2+0x121/0x1c0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1461
 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: 0033:0x7fb8d038eb69
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:00007fb8ce1f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fb8d05b6160 RCX: 00007fb8d038eb69
RDX: 0000000000000242 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007fb8d0411df1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fb8d05b6160 R15: 00007ffd6d60aa88
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/04 17:52 upstream d2eedaa3909b abdcb213 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root possible deadlock in ext4_readpage_inline
* Struck through repros no longer work on HEAD.