Hello, I found a potential bug titled " WARNING in ext4_mb_load_buddy_gfp " with modified syzkaller in the Linux6.12.24(longterm maintenance, last updated on April 20, 2025). It seems to be a problem with the ext4 subsystem. Unfortunately, I am unable to reproduce this bug. If you fix this issue, please add the following tag to the commit: Reported-by: Jianzhou Zhao xnxc22xnxc22@qq.com, xingwei lee xrivendell7@gmail.com,Penglei Jiang superman.xpt@gmail.com The commit of the kernel is : b6efa8ce222e58cfe2bbaa4e3329818c2b4bd74e kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=55f8591b98dd132 compiler: gcc version 11.4.0
------------[ cut here ]----------------------------------------- TITLE: WARNING in ext4_mb_load_buddy_gfp ------------[ cut here ]------------ WARNING: CPU: 0 PID: 96 at mm/page_alloc.c:4240 __alloc_pages_slowpath mm/page_alloc.c:4240 [inline] WARNING: CPU: 0 PID: 96 at mm/page_alloc.c:4240 __alloc_pages_noprof+0x1a1d/0x21f0 mm/page_alloc.c:4767 Modules linked in: CPU: 0 UID: 0 PID: 96 Comm: kswapd0 Not tainted 6.12.24 #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:__alloc_pages_slowpath mm/page_alloc.c:4240 [inline] RIP: 0010:__alloc_pages_noprof+0x1a1d/0x21f0 mm/page_alloc.c:4767 Code: 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 a2 07 00 00 f6 43 2d 08 0f 84 bd ea ff ff 90 <0f> 0b 90 e9 b4 ea ff ff 65 8b 15 70 e5 23 7e 83 fa 07 0f 87 56 06 RSP: 0000:ffffc90001376e18 EFLAGS: 00010202 RAX: 0000000000000007 RBX: ffff888042ac4a00 RCX: ffffc90001376f44 RDX: 0000000000000000 RSI: 1ffff9200026edb0 RDI: ffff888042ac4a2c RBP: ffff88803fffbc80 R08: 000000000000699a R09: 0000000000000400 R10: ffff88807ffda357 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffffffffffff R14: 0000000000048c40 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff88802b800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4969a4e7b0 CR3: 000000002719c000 CR4: 0000000000752ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <task> alloc_pages_mpol_noprof+0x2b6/0x600 mm/mempolicy.c:2269 folio_alloc_noprof+0x21/0xc0 mm/mempolicy.c:2356 filemap_alloc_folio_noprof+0x3d2/0x470 mm/filemap.c:1010 __filemap_get_folio+0x57f/0xb00 mm/filemap.c:1952 ext4_mb_load_buddy_gfp+0x74d/0x10c0 fs/ext4/mballoc.c:1640 ext4_discard_preallocations+0x539/0xf00 fs/ext4/mballoc.c:5592 ext4_clear_inode+0x3d/0x230 fs/ext4/super.c:1523 ext4_evict_inode+0x243/0x18c0 fs/ext4/inode.c:323 evict+0x3ef/0x940 fs/inode.c:725 dispose_list+0x117/0x1e0 fs/inode.c:774 prune_icache_sb+0xeb/0x150 fs/inode.c:963 super_cache_scan+0x37f/0x570 fs/super.c:223 do_shrink_slab+0x44b/0x1190 mm/shrinker.c:437 shrink_slab_memcg mm/shrinker.c:550 [inline] shrink_slab+0xb61/0x12a0 mm/shrinker.c:628 shrink_one+0x4ad/0x7c0 mm/vmscan.c:4835 shrink_many mm/vmscan.c:4896 [inline] lru_gen_shrink_node mm/vmscan.c:4974 [inline] shrink_node+0x2420/0x3890 mm/vmscan.c:5954 kswapd_shrink_node mm/vmscan.c:6782 [inline] balance_pgdat+0xbe5/0x18c0 mm/vmscan.c:6974 kswapd+0x702/0xd50 mm/vmscan.c:7243 kthread+0x2c7/0x3b0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </task>
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I hope it helps. Best regards Jianzhou Zhao/superman.xpt@gmail.com/xrivendell7@gmail.com/xnxc22xnxc22@qq.com