Re: [moderation/CI] Re: mm: store zswap entries in swap table (Pointer entry)

#syz upstream

On Tue, Jul 7, 2026 at 9:44 PM syzbot ci
<[email protected]> wrote:
>
> syzbot ci has tested the following series
>
> [v1] mm: store zswap entries in swap table (Pointer entry)
> https://lore.kernel.org/all/[email protected]
> * [RFC PATCH 1/7] mm/swap_table: add Pointer type support for zswap entry storage
> * [RFC PATCH 2/7] mm/zswap: add swp_tb_val to zswap_entry and Pointer accessor helpers
> * [RFC PATCH 3/7] mm/swap_state: do zswap conversion in __swap_cache_do_del_folio
> * [RFC PATCH 4/7] mm/zswap, mm/swap_state: handle Pointer entries in add_folio path
> * [RFC PATCH 5/7] mm/swapfile: handle Pointer entries in count/dup/put paths
> * [RFC PATCH 6/7] mm/zswap, mm/swap_state: migrate zswap to use swap_table for entry indexing
> * [RFC PATCH 7/7] mm/zswap, mm/swap_state: replace xarray indexing with swap table lookups
>
> and found the following issue:
> WARNING in __swap_cache_do_del_folio
>
> Full report is available here:
> https://ci.syzbot.org/series/1a9cfadb-ed85-48c1-b1b3-a3c12ea99471
>
> ***
>
> WARNING in __swap_cache_do_del_folio
>
> tree:      mm-new
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/akpm/mm.git
> base:      01bc0932614c2d3c35e732f54d249b5897d94307
> arch:      amd64
> compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
> config:    https://ci.syzbot.org/builds/65f10583-d539-4b33-8ba9-494d42eb9593/config
> syz repro: https://ci.syzbot.org/findings/3673912c-5490-4f26-ba24-276021c43d9b/syz_repro
>
> ------------[ cut here ]------------
> !swp_tb_is_folio(old_tb) || swp_tb_to_folio(old_tb) != folio
> WARNING: mm/swap_state.c:327 at __swap_cache_do_del_folio+0x6ef/0xdf0 mm/swap_state.c:326, CPU#1: syz.2.63/6057
> Modules linked in:
> CPU: 1 UID: 0 PID: 6057 Comm: syz.2.63 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:__swap_cache_do_del_folio+0x6ef/0xdf0 mm/swap_state.c:326
> Code: ff c9 48 09 c1 4c 21 f9 48 39 4c 24 08 0f 85 8c 02 00 00 e8 73 9a 9b ff 49 bf 00 00 00 00 00 fc ff df eb 3d e8 62 9a 9b ff 90 <0f> 0b 90 41 89 ed 41 83 e5 01 31 ff 4c 89 ee e8 2d 9f 9b ff 31 ff
> RSP: 0018:ffffc90003ea6690 EFLAGS: 00010093
> RAX: ffffffff822acdb9 RBX: 000000000000001f RCX: ffff88816d7d9e00
> RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffffea0006be5f08
> RBP: 00000000006be5f2 R08: ffff88801c7d20ff R09: 1ffff110038fa41f
> R10: dffffc0000000000 R11: ffffed10038fa420 R12: 0000000000000000
> R13: 0000000006be5f00 R14: 0000000000000002 R15: dffffc0000000000
> FS:  00007fef4622c6c0(0000) GS:ffff8882a921d000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000200000000280 CR3: 0000000176c44000 CR4: 00000000000006f0
> Call Trace:
>  <TASK>
>  __swap_cache_del_folio+0xd5/0x170 mm/swap_state.c:377
>  __remove_mapping+0xabb/0xe20 mm/vmscan.c:736
>  shrink_folio_list+0x2b42/0x5350 mm/vmscan.c:1489
>  reclaim_folio_list+0x100/0x430 mm/vmscan.c:2163
>  reclaim_pages+0x2f1/0x530 mm/vmscan.c:2196
>  madvise_cold_or_pageout_pte_range+0x1c1e/0x22e0 mm/madvise.c:562
>  walk_pmd_range mm/pagewalk.c:148 [inline]
>  walk_pud_range mm/pagewalk.c:239 [inline]
>  walk_p4d_range mm/pagewalk.c:280 [inline]
>  walk_pgd_range+0x100f/0x1e40 mm/pagewalk.c:321
>  __walk_page_range+0x16d/0x720 mm/pagewalk.c:429
>  walk_page_range_vma_unsafe+0x309/0x410 mm/pagewalk.c:733
>  madvise_pageout_page_range mm/madvise.c:621 [inline]
>  madvise_pageout mm/madvise.c:646 [inline]
>  madvise_vma_behavior+0x2922/0x4340 mm/madvise.c:1357
>  madvise_walk_vmas+0x576/0xb00 mm/madvise.c:1712
>  madvise_do_behavior+0x385/0x540 mm/madvise.c:1907
>  do_madvise+0x327/0x3a0 mm/madvise.c:2005
>  __do_sys_madvise mm/madvise.c:2014 [inline]
>  __se_sys_madvise mm/madvise.c:2012 [inline]
>  __x64_sys_madvise+0xa6/0xc0 mm/madvise.c:2012
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fef4539ce59
> 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:00007fef4622c028 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
> RAX: ffffffffffffffda RBX: 00007fef45616180 RCX: 00007fef4539ce59
> RDX: 0000000000000015 RSI: 0000000000600000 RDI: 0000200000000000
> RBP: 00007fef45432e6f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007fef45616218 R14: 00007fef45616180 R15: 00007ffcd47ce068
>  </TASK>
>
>
> ***
>
> 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: [email protected]
>
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