WARNING in ext4_mb_load_buddy_gfp

Status: upstream: reported C repro on 2025/09/15 07:39
Subsystems: ext4 mm
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+fd3f70a4509fca8c265d@syzkaller.appspotmail.com
First crash: 332d, last: 164d
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
c7181046 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ✅ VMHostTrigger: ❌ ❓ WARNING in ext4_mb_load_buddy_gfp 2026/05/24 16:01 2026/05/24 16:01 2026/05/24 16:33 c69befb3
▶ ▼ Discussions (6)
Title Replies (including bot) Last reply
Re: [PATCH] ext4: fix allocation failure in ext4_mb_load_buddy_gfp 2 (2) 2025/09/27 03:01
Re: [PATCH] ext4: fix allocation failure in ext4_mb_load_buddy_gfp 1 (1) 2025/09/27 00:19
[PATCH] ext4: fix allocation failure in ext4_mb_load_buddy_gfp 2 (2) 2025/09/24 23:33
[PATCH] ext4: fix allocation failure in ext4_mb_load_buddy_gfp 1 (1) 2025/09/19 02:14
[PATCH] ext4: fix allocation failure in ext4_mb_load_buddy_gfp 1 (2) 2025/09/19 01:53
[syzbot] [mm?] WARNING in ext4_mb_load_buddy_gfp 0 (3) 2025/09/19 01:32
▶ ▼ Last patch testing requests (12)
Created Duration User Patch Repo Result
2026/07/18 12:27 22m retest repro upstream error
2026/07/18 12:27 21m retest repro upstream error
2026/07/04 10:45 29m retest repro upstream no crash log
2026/05/09 09:09 23m retest repro upstream error
2026/05/09 09:09 22m retest repro upstream error
2026/04/25 08:07 21m retest repro upstream error
2026/02/28 08:06 15m retest repro upstream report log
2026/02/28 08:06 16m retest repro upstream report log
2026/02/14 07:50 15m retest repro upstream log
2025/12/20 07:23 20m retest repro upstream report log
2025/09/19 01:32 20m kartikey406@gmail.com patch upstream OK log
2025/09/19 01:25 1m kartikey406@gmail.com patch upstream error

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 5744 at mm/page_alloc.c:4630 __alloc_pages_slowpath+0xca5/0xce0 mm/page_alloc.c:4630
Modules linked in:
CPU: 0 UID: 0 PID: 5744 Comm: syz.5.31 Not tainted syzkaller #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
RIP: 0010:__alloc_pages_slowpath+0xca5/0xce0 mm/page_alloc.c:4630
Code: 48 8b 1c 25 08 60 a1 92 48 83 c3 2c 48 89 d8 48 c1 e8 03 0f b6 04 08 84 c0 75 2e f6 43 01 08 48 8b 14 24 0f 84 a2 f3 ff ff 90 <0f> 0b 90 e9 99 f3 ff ff e8 1e 55 64 09 90 0f 0b 90 f7 c5 00 04 00
RSP: 0018:ffffc9000d656050 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff888000bba46c RCX: dffffc0000000000
RDX: ffffc9000d656160 RSI: 0000000000000000 RDI: 0000000000048c40
RBP: 0000000000048c40 R08: ffff88801b2f30cf R09: 1ffff1100365e619
R10: dffffc0000000000 R11: ffffed100365e61a R12: ffffc9000d656160
R13: 1ffff92001acac28 R14: 0000000000048c40 R15: dffffc0000000000
FS:  00007f7ccbb366c0(0000) GS:ffff88808d20a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f94b93a8638 CR3: 0000000042c26000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __alloc_frozen_pages_noprof+0x319/0x370 mm/page_alloc.c:5161
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0xa9/0x190 mm/mempolicy.c:2507
 folio_alloc_noprof+0x1e/0x30 mm/mempolicy.c:2517
 filemap_alloc_folio_noprof+0xdf/0x470 mm/filemap.c:1007
 __filemap_get_folio+0x3f2/0xaf0 mm/filemap.c:1981
 ext4_mb_load_buddy_gfp+0x281/0xeb0 fs/ext4/mballoc.c:1709
 ext4_discard_preallocations+0x66b/0xec0 fs/ext4/mballoc.c:5660
 ext4_clear_inode+0x40/0x1c0 fs/ext4/super.c:1503
 ext4_evict_inode+0xa67/0xee0 fs/ext4/inode.c:321
 evict+0x504/0x9c0 fs/inode.c:810
 dispose_list fs/inode.c:852 [inline]
 prune_icache_sb+0x21b/0x2c0 fs/inode.c:1000
 super_cache_scan+0x39b/0x4b0 fs/super.c:224
 do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437
 shrink_slab_memcg mm/shrinker.c:550 [inline]
 shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628
 shrink_one+0x28a/0x7c0 mm/vmscan.c:4954
 shrink_many mm/vmscan.c:5015 [inline]
 lru_gen_shrink_node mm/vmscan.c:5093 [inline]
 shrink_node+0x314e/0x3760 mm/vmscan.c:6078
 shrink_zones mm/vmscan.c:6336 [inline]
 do_try_to_free_pages+0x668/0x1960 mm/vmscan.c:6398
 try_to_free_pages+0x8a2/0xdd0 mm/vmscan.c:6644
 __perform_reclaim mm/page_alloc.c:4310 [inline]
 __alloc_pages_direct_reclaim+0x144/0x300 mm/page_alloc.c:4332
 __alloc_pages_slowpath+0x5ff/0xce0 mm/page_alloc.c:4781
 __alloc_frozen_pages_noprof+0x319/0x370 mm/page_alloc.c:5161
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof mm/mempolicy.c:2435 [inline]
 vma_alloc_folio_noprof+0xe4/0x200 mm/mempolicy.c:2470
 folio_prealloc+0x30/0x180 mm/memory.c:-1
 alloc_anon_folio mm/memory.c:4997 [inline]
 do_anonymous_page mm/memory.c:5054 [inline]
 do_pte_missing mm/memory.c:4232 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x2ab9/0x5440 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]
 faultin_page_range+0x240/0x8d0 mm/gup.c:1932
 madvise_populate mm/madvise.c:979 [inline]
 madvise_do_behavior+0x2e7/0x550 mm/madvise.c:1883
 do_madvise+0x1bc/0x270 mm/madvise.c:1978
 __do_sys_madvise mm/madvise.c:1987 [inline]
 __se_sys_madvise mm/madvise.c:1985 [inline]
 __x64_sys_madvise+0xa7/0xc0 mm/madvise.c:1985
 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: 0033:0x7f7ccad8eba9
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:00007f7ccbb36038 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f7ccafd5fa0 RCX: 00007f7ccad8eba9
RDX: 0000000000000017 RSI: 0000000000c00000 RDI: 0000200000000000
RBP: 00007f7ccae11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7ccafd6038 R14: 00007f7ccafd5fa0 R15: 00007ffd394e0938
 </TASK>

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/13 05:02 upstream 22f20375f5b7 e2beed91 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci-snapshot-upstream-root WARNING in ext4_mb_load_buddy_gfp
2025/09/13 03:34 upstream 22f20375f5b7 e2beed91 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci-snapshot-upstream-root WARNING in ext4_mb_load_buddy_gfp
2025/11/15 23:44 upstream f824272b6e3f f7988ea4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_mb_load_buddy_gfp
2025/11/14 14:59 upstream 6da43bbeb691 6d98c1c8 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_mb_load_buddy_gfp
2025/10/30 18:48 upstream e53642b87a4f 2c50b6a9 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_mb_load_buddy_gfp
2025/09/13 06:08 upstream 22f20375f5b7 e2beed91 .config console log report syz / log [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci-snapshot-upstream-root WARNING in ext4_mb_load_buddy_gfp
2025/09/13 02:37 upstream 22f20375f5b7 e2beed91 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in ext4_mb_load_buddy_gfp
* Struck through repros no longer work on HEAD.