reply: [syzbot ci] Re: mm: bail out when the PMD has been set in bloom filter

reply: [syzbot ci] Re: mm: bail out when the PMD has been set in bloom filter

[黄朝阳 (Zhaoyang Huang)]

>
>
>syzbot ci has tested the following series
>
>[v1] mm: bail out when the PMD has been set in bloom filter
>https://lore.kernel.org/all/20260227075250.1128175-1-zhaoyang.huang@uni
>soc.com
>* [PATCH] mm: bail out when the PMD has been set in bloom filter
>
>and found the following issue:
>general protection fault in lru_gen_look_around
>
>Full report is available here:
>https://ci.syzbot.org/series/78ce04ff-c36e-4bcc-a097-f457e3ed9e5e
>
>***
>
>general protection fault in lru_gen_look_around
>
>tree:      mm-new
>URL:
>https://kernel.googlesource.com/pub/scm/linux/kernel/git/akpm/mm.git
>base:      8982358e1c87e3e1dc0aad37f4f93efe9c1cfe03
>arch:      amd64
>compiler:  Debian clang version 21.1.8
>(++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian
>LLD 21.1.8
>config:
>https://ci.syzbot.org/builds/e976d408-587c-416f-85ab-a60940674f35/config
>C repro:
>https://ci.syzbot.org/findings/ea92e1a7-69bd-4608-bc2c-2ff4ca118f9c/c_repr
>o
>syz repro:
>https://ci.syzbot.org/findings/ea92e1a7-69bd-4608-bc2c-2ff4ca118f9c/syz_re
>pro
>
>Oops: general protection fault, probably for non-canonical address
>0xdffffc0000000003: 0000 [#1] SMP KASAN PTI
>KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
>CPU: 1 UID: 0 PID: 5967 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full)
>Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
>1.16.2-debian-1.16.2-1 04/01/2014
>RIP: 0010:test_bloom_filter mm/vmscan.c:2785 [inline]
>RIP: 0010:lru_gen_look_around+0x45c/0xd20 mm/vmscan.c:4206
>Code: 22 be ff 48 c7 44 24 48 00 00 00 00 48 83 c3 28 48 89 dd 48 c1 ed 03 42
>80 7c 25 00 00 74 08 48 89 df e8 97 b5 28 00 4c 8b 3b <41> 80 7c 24 03 00 74
>0a bf 18 00 00 00 e8 82 b5 28 00 4c 8b 24 25
>RSP: 0018:ffffc900046e5c90 EFLAGS: 00010246
>RAX: 0000000000000000 RBX: ffffc900046e5e68 RCX: ffff8881100b1d00
>RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
>RBP: 1ffff920008dcbcd R08: ffff88811008fcc3 R09: 1ffff11022011f98
>R10: dffffc0000000000 R11: ffffed1022011f99 R12: dffffc0000000000
>R13: 0000555585af4000 R14: ffffea0006a69fc0 R15: ffff888114457168
>FS:  0000555585ad9500(0000) GS:ffff8882a9461000(0000)
>knlGS:0000000000000000
>CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>CR2: 00007f4753817dac CR3: 00000001b9a5e000 CR4: 00000000000006f0
>Call Trace:
> <TASK>
> folio_referenced_one+0x724/0x1360 mm/rmap.c:962
> rmap_walk_anon+0x5cb/0x7c0 mm/rmap.c:2973  rmap_walk
>mm/rmap.c:3078 [inline]
> folio_referenced+0x3c0/0x5f0 mm/rmap.c:1081  folio_check_references
>mm/vmscan.c:870 [inline]
> shrink_folio_list+0x1008/0x5240 mm/vmscan.c:1237
> evict_folios+0x3f82/0x5090 mm/vmscan.c:4853
> try_to_shrink_lruvec+0xb62/0xfa0 mm/vmscan.c:5008
>lru_gen_shrink_lruvec mm/vmscan.c:5157 [inline]
> shrink_lruvec+0x54e/0x2b30 mm/vmscan.c:5911  shrink_node_memcgs
>mm/vmscan.c:6147 [inline]
> shrink_node+0xa41/0x3a90 mm/vmscan.c:6188  shrink_zones
>mm/vmscan.c:6427 [inline]
> do_try_to_free_pages+0x6a2/0x1980 mm/vmscan.c:6489
> try_to_free_mem_cgroup_pages+0x2ff/0x870 mm/vmscan.c:6811
> try_charge_memcg+0x827/0x1560 mm/memcontrol.c:2642
>obj_cgroup_charge_pages mm/memcontrol.c:3084 [inline]
> __memcg_kmem_charge_page+0x32a/0x530 mm/memcontrol.c:3128
> __alloc_frozen_pages_noprof+0x1c1/0x380 mm/page_alloc.c:5271
>__alloc_pages_noprof mm/page_alloc.c:5288 [inline]
> alloc_pages_bulk_noprof+0x569/0x710 mm/page_alloc.c:5208
> alloc_pages_bulk_mempolicy_noprof+0x34e/0x1680 mm/mempolicy.c:2792
>vm_area_alloc_pages mm/vmalloc.c:3700 [inline]  __vmalloc_area_node
>mm/vmalloc.c:3875 [inline]
> __vmalloc_node_range_noprof+0xbd9/0x1a80 mm/vmalloc.c:4058
>__bpf_map_area_alloc kernel/bpf/syscall.c:404 [inline]
> bpf_map_area_alloc+0x12d/0x170 kernel/bpf/syscall.c:411
> bloom_map_alloc+0x22f/0x470 kernel/bpf/bloom_filter.c:146
> map_create+0xafd/0x16a0 kernel/bpf/syscall.c:1507
> __sys_bpf+0x6e1/0x950 kernel/bpf/syscall.c:6210  __do_sys_bpf
>kernel/bpf/syscall.c:6341 [inline]  __se_sys_bpf kernel/bpf/syscall.c:6339
>[inline]
> __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6339
> 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: 0033:0x7f475359c799
>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:00007fff2e480d98 EFLAGS: 00000246 ORIG_RAX:
>0000000000000141
>RAX: ffffffffffffffda RBX: 00007f4753815fa0 RCX: 00007f475359c799
>RDX: 0000000000000050 RSI: 0000200000000dc0 RDI: 0000000000000000
>RBP: 00007f4753632bd9 R08: 0000000000000000 R09: 0000000000000000
>R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>R13: 00007f4753815fac R14: 00007f4753815fa0 R15: 00007f4753815fa0
></TASK> Modules linked in:
>---[ end trace 0000000000000000 ]---
>RIP: 0010:test_bloom_filter mm/vmscan.c:2785 [inline]
>RIP: 0010:lru_gen_look_around+0x45c/0xd20 mm/vmscan.c:4206
>Code: 22 be ff 48 c7 44 24 48 00 00 00 00 48 83 c3 28 48 89 dd 48 c1 ed 03 42
>80 7c 25 00 00 74 08 48 89 df e8 97 b5 28 00 4c 8b 3b <41> 80 7c 24 03 00 74
>0a bf 18 00 00 00 e8 82 b5 28 00 4c 8b 24 25
>RSP: 0018:ffffc900046e5c90 EFLAGS: 00010246
>RAX: 0000000000000000 RBX: ffffc900046e5e68 RCX: ffff8881100b1d00
>RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
>RBP: 1ffff920008dcbcd R08: ffff88811008fcc3 R09: 1ffff11022011f98
>R10: dffffc0000000000 R11: ffffed1022011f99 R12: dffffc0000000000
>R13: 0000555585af4000 R14: ffffea0006a69fc0 R15: ffff888114457168
>FS:  0000555585ad9500(0000) GS:ffff8882a9461000(0000)
>knlGS:0000000000000000
>CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>CR2: 00007f4753817dac CR3: 00000001b9a5e000 CR4: 00000000000006f0
>----------------
>Code disassembly (best guess):
>   0:   22 be ff 48 c7 44       and    0x44c748ff(%rsi),%bh
>   6:   24 48                   and    $0x48,%al
>   8:   00 00                   add    %al,(%rax)
>   a:   00 00                   add    %al,(%rax)
>   c:   48 83 c3 28             add    $0x28,%rbx
>  10:   48 89 dd                mov    %rbx,%rbp
>  13:   48 c1 ed 03             shr    $0x3,%rbp
>  17:   42 80 7c 25 00 00       cmpb   $0x0,0x0(%rbp,%r12,1)
>  1d:   74 08                   je     0x27
>  1f:   48 89 df                mov    %rbx,%rdi
>  22:   e8 97 b5 28 00          call   0x28b5be
>  27:   4c 8b 3b                mov    (%rbx),%r15
>* 2a:   41 80 7c 24 03 00       cmpb   $0x0,0x3(%r12) <-- trapping
>instruction
>  30:   74 0a                   je     0x3c
>  32:   bf 18 00 00 00          mov    $0x18,%edi
>  37:   e8 82 b5 28 00          call   0x28b5be
>  3c:   4c                      rex.WR
>  3d:   8b                      .byte 0x8b
>  3e:   24 25                   and    $0x25,%al
#syz test

diff --git a/mm/vmscan.c b/mm/vmscan.c
index fcf6b6f21eb9..5558a24d1564 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4235,7 +4235,7 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw)
        walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL;
 
        /* may the pmd has been set in bloom filter */
-       if (test_bloom_filter(mm_state, max_seq, pvmw->pmd))
+       if (mm_state && test_bloom_filter(mm_state, max_seq, pvmw->pmd))
                return true;
 
        start = max(addr & PMD_MASK, vma->vm_start);

>
>
>***
>
>If these findings have caused you to resend the series or submit a separate fix,
>please add the following tag to your commit message:
>  Tested-by: syzbot@syzkaller.appspotmail.com
>
>---
>This report is generated by a bot. It may contain errors.
>syzbot ci engineers can be reached at syzkaller@googlegroups.com.

Re: reply: [syzbot ci] Re: mm: bail out when the PMD has been set in bloom filter

[syzbot ci]

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