Re: [syzbot] Re: [syzbot] [mm?] [bcachefs?] WARNING in lock_list_lru_of_memcg

[syzbot <syzbot+38a0cbd267eff2d286ff@syzkaller.appspotmail.com>]

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Subject: Re: [syzbot] [mm?] [bcachefs?] WARNING in lock_list_lru_of_memcg
Author: mmpgouride@gmail.com



> On Feb 15, 2025, at 02:11, syzbot <syzbot+38a0cbd267eff2d286ff@syzkaller.appspotmail.com> wrote:
> 
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    128c8f96eb86 Merge tag 'drm-fixes-2025-02-14' of https://g..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=148019a4580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c776e555cfbdb82d
> dashboard link: https://syzkaller.appspot.com/bug?extid=38a0cbd267eff2d286ff
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12328bf8580000
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-128c8f96.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/a97f78ac821e/vmlinux-128c8f96.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/f451cf16fc9f/bzImage-128c8f96.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/a7da783f97cf/mount_3.gz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+38a0cbd267eff2d286ff@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 5459 at mm/list_lru.c:96 lock_list_lru_of_memcg+0x39e/0x4d0 mm/list_lru.c:96
> Modules linked in:
> CPU: 0 UID: 0 PID: 5459 Comm: syz-executor Not tainted 6.14.0-rc2-syzkaller-00185-g128c8f96eb86 #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> RIP: 0010:lock_list_lru_of_memcg+0x39e/0x4d0 mm/list_lru.c:96
> Code: e9 19 fe ff ff e8 72 f2 b5 ff 4c 8b 7c 24 08 45 84 f6 0f 84 40 ff ff ff e9 22 01 00 00 e8 5a f2 b5 ff eb 05 e8 53 f2 b5 ff 90 <0f> 0b 90 eb 97 89 e9 80 e1 07 80 c1 03 38 c1 0f 8c 71 fd ff ff 48
> RSP: 0018:ffffc9000d70f3a0 EFLAGS: 00010293
> RAX: ffffffff820bc50d RBX: 0000000000000000 RCX: ffff8880382d4880
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: ffff8880351ac054 R08: ffffffff820bc49f R09: 1ffffffff2079b8e
> R10: dffffc0000000000 R11: fffffbfff2079b8f R12: ffffffff820bc19e
> R13: ffff88801ee9a798 R14: 0000000000000000 R15: ffff8880351ac000
> FS:  000055557d70b500(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fff6826de40 CR3: 000000005680c000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> list_lru_del+0x58/0x1f0 mm/list_lru.c:202
> list_lru_del_obj+0x17b/0x250 mm/list_lru.c:223
> d_lru_del fs/dcache.c:481 [inline]
> to_shrink_list+0x136/0x340 fs/dcache.c:904
> select_collect+0xce/0x1b0 fs/dcache.c:1472
> d_walk+0x1f5/0x750 fs/dcache.c:1295
> shrink_dcache_parent+0x144/0x3b0 fs/dcache.c:1527
> d_invalidate+0x11c/0x2d0 fs/dcache.c:1632
> proc_invalidate_siblings_dcache+0x3fb/0x6e0 fs/proc/inode.c:142
> release_task+0x168e/0x1830 kernel/exit.c:279
> wait_task_zombie kernel/exit.c:1249 [inline]
> wait_consider_task+0x1a14/0x2e60 kernel/exit.c:1476
> do_wait_thread kernel/exit.c:1539 [inline]
> __do_wait+0x1b0/0x850 kernel/exit.c:1657
> do_wait+0x1e9/0x550 kernel/exit.c:1691
> kernel_wait4+0x2a7/0x3e0 kernel/exit.c:1850
> __do_sys_wait4 kernel/exit.c:1878 [inline]
> __se_sys_wait4 kernel/exit.c:1874 [inline]
> __x64_sys_wait4+0x134/0x1e0 kernel/exit.c:1874
> do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f93f3983057
> Code: 89 7c 24 10 48 89 4c 24 18 e8 45 1b 03 00 4c 8b 54 24 18 8b 54 24 14 41 89 c0 48 8b 74 24 08 8b 7c 24 10 b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 89 44 24 10 e8 95 1b 03 00 8b 44
> RSP: 002b:00007fff6826e9b0 EFLAGS: 00000293 ORIG_RAX: 000000000000003d
> RAX: ffffffffffffffda RBX: 0000000000000019 RCX: 00007f93f3983057
> RDX: 0000000040000001 RSI: 00007fff6826ea1c RDI: 00000000ffffffff
> RBP: 00007fff6826ea1c R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000001388
> R13: 00000000000927c0 R14: 000000000002f011 R15: 00007fff6826ea70
> </TASK>
> 
> 
> ---
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
> 

#syz test

iff --git a/fs/bcachefs/btree_io.c b/fs/bcachefs/btree_io.c
index e71b278672b6..907868b53d1f 100644
--- a/fs/bcachefs/btree_io.c
+++ b/fs/bcachefs/btree_io.c
@@ -727,14 +727,14 @@ static int validate_bset(struct bch_fs *c, struct bch_dev *ca,
                     btree_node_unsupported_version,
                     "BSET_SEPARATE_WHITEOUTS no longer supported");
 
-       if (!write &&
-           btree_err_on(offset + sectors > (ptr_written ?: btree_sectors(c)),
-                        -BCH_ERR_btree_node_read_err_fixable,
-                        c, ca, b, i, NULL,
-                        bset_past_end_of_btree_node,
-                        "bset past end of btree node (offset %u len %u but written %zu)",
-                        offset, sectors, ptr_written ?: btree_sectors(c)))
+       if (!write && offset + sectors > (ptr_written ?: btree_sectors(c))) {
                i->u64s = 0;
+               btree_err(-BCH_ERR_btree_node_read_err_fixable,
+                         c, ca, b, i, NULL,
+                         bset_past_end_of_btree_node,
+                         "bset past end of btree node (offset %u len %u but written %zu)",
+                         offset, sectors, ptr_written ?: btree_sectors(c));
+       }
 
        btree_err_on(offset && !i->u64s,
                     -BCH_ERR_btree_node_read_err_fixable,
@@ -997,7 +997,7 @@ static int validate_bset_keys(struct bch_fs *c, struct btree *b,
                }
 got_good_key:
                le16_add_cpu(&i->u64s, -next_good_key);
-               memmove_u64s_down(k, bkey_p_next(k), (u64 *) vstruct_end(i) - (u64 *) k);
+               memmove_u64s_down(k, (u64 *) k + next_good_key, (u64 *) vstruct_end(i) - (u64 *) k);
                set_btree_node_need_rewrite(b);
        }
 fsck_err: