syzbot


WARNING in ext4_write_inode (3)

Status: upstream: reported on 2025/10/16 17:36
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+070d9738dbe6a10fadc8@syzkaller.appspotmail.com
First crash: 184d, last: 13d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] WARNING in ext4_write_inode (3) 0 (1) 2025/10/16 17:36
Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 WARNING in ext4_write_inode -1 6 2242d 2243d 0/1 auto-closed as invalid on 2020/06/22 22:10
upstream WARNING in ext4_write_inode ext4 -1 13 2232d 2239d 15/29 fixed on 2020/05/10 10:41
upstream WARNING in ext4_write_inode (2) ext4 -1 C 130 544d 1522d 0/29 auto-obsoleted due to no activity on 2025/01/25 16:58
linux-5.15 WARNING in ext4_write_inode -1 1 1113d 1113d 0/3 auto-obsoleted due to no activity on 2023/07/26 10:16
linux-4.19 WARNING in ext4_write_inode -1 1 2242d 2242d 0/1 auto-closed as invalid on 2020/06/22 14:27
linux-6.1 WARNING in ext4_write_inode -1 5 1036d 1117d 0/3 auto-obsoleted due to no activity on 2023/09/21 16:26

Sample crash report:
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 warn_alloc+0x249/0x340 mm/page_alloc.c:4046
 __alloc_pages_slowpath+0xcac/0xd40 mm/page_alloc.c:4990
 __alloc_frozen_pages_noprof+0x322/0x380 mm/page_alloc.c:5263
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2490
 folio_alloc_mpol_noprof mm/mempolicy.c:2509 [inline]
 alloc_migration_target_by_mpol+0x2e4/0x5e0 mm/mempolicy.c:1463
 migrate_folio_unmap mm/migrate.c:1215 [inline]
 migrate_pages_batch+0x9e7/0x4d80 mm/migrate.c:1890
 migrate_pages+0x23cb/0x2a70 mm/migrate.c:2131
 do_mbind mm/mempolicy.c:1614 [inline]
 kernel_mbind mm/mempolicy.c:1757 [inline]
 __do_sys_mbind mm/mempolicy.c:1831 [inline]
 __se_sys_mbind+0xe89/0x10f0 mm/mempolicy.c:1827
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe54bd9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe54cc15fe8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ed
RAX: ffffffffffffffda RBX: 00007fe54c015fa0 RCX: 00007fe54bd9c819
RDX: 0000000000000002 RSI: 0000000000600000 RDI: 0000200000000000
RBP: 00007fe54be32c91 R08: 0000000000000008 R09: 0000000000000002
R10: 0000200000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe54c016038 R14: 00007fe54c015fa0 R15: 00007ffc1939e0e8
 </TASK>
Mem-Info:
active_anon:4691 inactive_anon:0 isolated_anon:1536
 active_file:999 inactive_file:38360 isolated_file:0
 unevictable:1768 dirty:0 writeback:0
 slab_reclaimable:7435 slab_unreclaimable:30831
 mapped:12276 shmem:5160 pagetables:714
 sec_pagetables:291 bounce:0
 kernel_misc_reclaimable:0
 free:31330 free_pcp:101 free_cma:0
Node 0 active_anon:8kB inactive_anon:0kB active_file:12kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:8kB dirty:0kB writeback:0kB shmem:0kB shmem_thp:0kB shmem_pmdmapped:0kB anon_thp:0kB kernel_stack:3136kB pagetables:796kB sec_pagetables:1088kB all_unreclaimable? yes Balloon:0kB
Node 0 DMA free:1964kB boost:2048kB min:2808kB low:2996kB high:3184kB reserved_highatomic:0KB free_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB zspages:0kB present:15992kB managed:15360kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
lowmem_reserve[]: 0 113 113 113 113
Node 0 DMA32 free:4380kB boost:0kB min:4408kB low:5508kB high:6608kB reserved_highatomic:0KB free_highatomic:0KB active_anon:8kB inactive_anon:0kB active_file:12kB inactive_file:0kB unevictable:0kB writepending:0kB zspages:0kB present:770052kB managed:116576kB mlocked:0kB bounce:0kB free_pcp:404kB local_pcp:404kB free_cma:0kB
lowmem_reserve[]: 0 0 0 0 0
Node 0 DMA: 20*4kB (U) 9*8kB (UM) 5*16kB (U) 8*32kB (U) 3*64kB (U) 2*128kB (UM) 0*256kB 0*512kB 1*1024kB (M) 0*2048kB 0*4096kB = 1960kB
Node 0 DMA32: 13*4kB (U) 21*8kB (UM) 10*16kB (UME) 15*32kB (U) 5*64kB (UM) 1*128kB (U) 4*256kB (UME) 0*512kB 2*1024kB (UM) 0*2048kB 0*4096kB = 4380kB
Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB
Node 0 hugepages_total=2 hugepages_free=2 hugepages_surp=0 hugepages_size=2048kB
44630 total pagecache pages
89 pages in swap cache
Free swap  = 123748kB
Total swap = 124996kB
393083 pages RAM
0 pages HighMem/MovableOnly
187396 pages reserved
0 pages cma reserved
------------[ cut here ]------------
current->flags & PF_MEMALLOC
WARNING: fs/ext4/inode.c:5676 at ext4_write_inode+0x544/0x620 fs/ext4/inode.c:5676, CPU#0: syz.0.0/5319
Modules linked in:
CPU: 0 UID: 0 PID: 5319 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:ext4_write_inode+0x544/0x620 fs/ext4/inode.c:5676
Code: 8b 05 a0 4e 94 10 48 3b 44 24 30 75 5a 44 89 e0 48 83 c4 38 5b 41 5c 41 5d 41 5e 41 5f 5d e9 03 27 2b 09 cc e8 cd d2 3c ff 90 <0f> 0b 90 eb cf e8 c2 d2 3c ff 41 bc fb ff ff ff eb c2 e8 b5 d2 3c
RSP: 0018:ffffc9000f4de380 EFLAGS: 00010283
RAX: ffffffff8288f1a3 RBX: 0000000000000800 RCX: 0000000000100000
RDX: ffffc9000ec52000 RSI: 00000000000e97c0 RDI: 00000000000e97c1
RBP: 0000000000000001 R08: ffffffff9011f1b7 R09: 1ffffffff2023e36
R10: dffffc0000000000 R11: ffffffff8288ec60 R12: 0000000000000000
R13: ffffc9000f4de4c0 R14: ffff888047a0f5b8 R15: ffff88801f8da4c0
FS:  00007fe54cc166c0(0000) GS:ffff88808ca4c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a7e770c168 CR3: 0000000041985000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 write_inode fs/fs-writeback.c:1582 [inline]
 __writeback_single_inode+0x75a/0x11a0 fs/fs-writeback.c:1825
 writeback_single_inode+0x4ac/0xdc0 fs/fs-writeback.c:1881
 write_inode_now+0x1c2/0x290 fs/fs-writeback.c:2972
 iput_final fs/inode.c:1956 [inline]
 iput+0x8c1/0xe80 fs/inode.c:2015
 __dentry_kill+0x1a2/0x5e0 fs/dcache.c:670
 shrink_kill+0xa9/0x2c0 fs/dcache.c:1147
 shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1174
 prune_dcache_sb+0x119/0x180 fs/dcache.c:1256
 super_cache_scan+0x369/0x4b0 fs/super.c:223
 do_shrink_slab+0x6df/0x1170 mm/shrinker.c:437
 shrink_slab_memcg mm/shrinker.c:550 [inline]
 shrink_slab+0x830/0x1150 mm/shrinker.c:628
 shrink_one+0x2d9/0x710 mm/vmscan.c:4928
 shrink_many mm/vmscan.c:4989 [inline]
 lru_gen_shrink_node mm/vmscan.c:5067 [inline]
 shrink_node+0x3197/0x3a90 mm/vmscan.c:6047
 shrink_zones mm/vmscan.c:6300 [inline]
 do_try_to_free_pages+0x6a2/0x1980 mm/vmscan.c:6362
 try_to_free_pages+0x8f2/0xe90 mm/vmscan.c:6601
 __perform_reclaim mm/page_alloc.c:4424 [inline]
 __alloc_pages_direct_reclaim+0x148/0x310 mm/page_alloc.c:4446
 __alloc_pages_slowpath+0x57d/0xd40 mm/page_alloc.c:4846
 __alloc_frozen_pages_noprof+0x322/0x380 mm/page_alloc.c:5263
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2490
 folio_alloc_mpol_noprof mm/mempolicy.c:2509 [inline]
 alloc_migration_target_by_mpol+0x2e4/0x5e0 mm/mempolicy.c:1463
 migrate_folio_unmap mm/migrate.c:1215 [inline]
 migrate_pages_batch+0x9e7/0x4d80 mm/migrate.c:1890
 migrate_pages+0x23cb/0x2a70 mm/migrate.c:2131
 do_mbind mm/mempolicy.c:1614 [inline]
 kernel_mbind mm/mempolicy.c:1757 [inline]
 __do_sys_mbind mm/mempolicy.c:1831 [inline]
 __se_sys_mbind+0xe89/0x10f0 mm/mempolicy.c:1827
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe54bd9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe54cc15fe8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ed
RAX: ffffffffffffffda RBX: 00007fe54c015fa0 RCX: 00007fe54bd9c819
RDX: 0000000000000002 RSI: 0000000000600000 RDI: 0000200000000000
RBP: 00007fe54be32c91 R08: 0000000000000008 R09: 0000000000000002
R10: 0000200000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe54c016038 R14: 00007fe54c015fa0 R15: 00007ffc1939e0e8
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/01 20:42 upstream 9147566d8016 0285fe54 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_write_inode
2026/03/11 19:17 upstream b29fb8829bff 2d88ab01 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_write_inode
2026/02/27 21:05 upstream a75cb869a8cc 2cf092b8 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_write_inode
2026/02/26 20:07 upstream f4d0ec0aa20d ffa54287 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_write_inode
2026/01/10 02:06 upstream 54e82e93ca93 d1b870e1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_write_inode
2025/10/12 17:25 upstream 67029a49db6c ff1712fe .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_write_inode
* Struck through repros no longer work on HEAD.