From: Breno Leitao <leitao@debian.org>
To: Kairui Song <kasong@tencent.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Kemeng Shi <shikemeng@huaweicloud.com>,
Nhat Pham <nphamcs@gmail.com>, Baoquan He <bhe@redhat.com>,
Barry Song <baohua@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Youngjun Park <youngjun.park@lge.com>,
linux-kernel@vger.kernel.org, Chris Li <chrisl@kernel.org>,
kernel-team@meta.com
Subject: Re: [PATCH v3 09/12] mm, swap: use the swap table to track the swap count
Date: Mon, 11 May 2026 04:19:50 -0700 [thread overview]
Message-ID: <agG6Dp0umhs6O1SY@gmail.com> (raw)
In-Reply-To: <20260218-swap-table-p3-v3-9-f4e34be021a7@tencent.com>
Hello Kairui,
On Wed, Feb 18, 2026 at 04:06:34AM +0800, Kairui Song wrote:
> @@ -479,6 +469,7 @@ static void swap_cluster_assert_empty(struct swap_cluster_info *ci,
> } while (++ci_off < ci_end);
>
> WARN_ON_ONCE(bad_slots != (swapoff ? ci->count : 0));
> + WARN_ON_ONCE(nr == SWAPFILE_CLUSTER && ci->extend_table);
On my automatic tests with 7.1 kernel I am seeing the following warning.
The test was running on commit 74fe02ce122a6103f20 ("Merge tag
'wq-for-7.1-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq").
This happened only once so far.
WARNING: mm/swapfile.c:471 at swap_cluster_assert_empty+0x1b6/0x1d0, CPU#2: swapoff/1265108 ^[[36m[warn]^[[0m
Modules linked in: sunrpc(E) squashfs(E) sch_fq(E) act_gact(E) tcp_diag(E) inet_diag(E) cls_bpf(E) intel_uncore_frequency(E) intel_uncore_frequency_common(E) skx_edac(E) skx_edac_common(E) nfit(E) x86_pkg_temp_thermal(E) intel_powerclamp(E) coretemp(E) kvm_intel(E) kvm(E) evdev(E) iTCO_wdt(E) ipmi_si(E) irqbypass(E) ipmi_devintf(E) xhci_pci(E) acpi_cpufreq(E) wmi(E) ipmi_msghandler(E) button(E) i2c_i801(E) xhci_hcd(E) i2c_smbus(E) sch_fq_codel(E) ip_tables(E) ip6_tables(E) vhost_net(E) tun(E) vhost(E) vhost_iotlb(E) tap(E) tls(E) mpls_gso(E) bpf_preload(E) mpls_iptunnel(E) mpls_router(E) fou(E) drm(E) loop(E) backlight(E) drm_panel_orientation_quirks(E) autofs4(E) raid0(E) efivarfs(E) dm_crypt(E)
CPU: 2 UID: 0 PID: 1265108 Comm: swapoff Tainted: G S E 7.1.0-0_fbk701_debugnightly_rc0_upstream_76_g74fe02ce122a #1 PREEMPTLAZY
Tainted: [S]=CPU_OUT_OF_SPEC, [E]=UNSIGNED_MODULE
Hardware name: Quanta Twin Lakes MP/Twin Lakes Passive MP, BIOS F09M3A09 07/03/2023
RIP: 0010:swap_cluster_assert_empty+0x1b6/0x1d0
Code: e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 84 c0 75 1a 41 0f b7 07 39 c3 74 99 0f 0b 81 7c 24 08 00 02 00 00 74 97 eb be <0f> 0b eb ba 44 89 f9 80 e1 07 fe c1 38 c1 7c da 4c 89 ff e8 12 46
RSP: 0018:ffff8882a2257a48 EFLAGS: 00010286
RAX: 1ffff1106956192d RBX: 0000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff8884dbeeaff8
RBP: ffff8884dbeeaff8 R08: ffff8884dbeeafff R09: 1ffff1109b7dd5ff
R10: dffffc0000000000 R11: ffffed109b7dd600 R12: ffff88834ab0c960
R13: 0000000000000200 R14: ffff88834ab0c968 R15: 0000000000000200
FS: 00007fab994cf800(0000) GS:ffff88909c8c0000(0000) knlGS:0000000000000000
CR2: 00007f789da9b110 CR3: 00000004bdc63001 CR4: 00000000007726f0
PKRU: 55555554
Call Trace:
<TASK>
__free_cluster+0x2f/0x180
swap_cache_del_folio+0x120/0x240
folio_free_swap+0x51b/0x630
? folio_free_swap+0x2e6/0x630
try_to_unuse+0x216d/0x2470
? try_to_unuse+0xbc9/0x2470
__se_sys_swapoff+0x3fb/0x8e0
do_syscall_64+0xfa/0x990
? irqentry_exit+0x102/0x770
? trace_irq_disable+0x64/0x1c0
? entry_SYSCALL_64_after_hwframe+0x4b/0x53
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7fab996ac08b
Code: 0f 1e fa 48 83 fe 01 48 8b 15 89 ad 0c 00 19 c0 83 e0 f0 83 c0 26 64 89 02 b8 ff ff ff ff c3 f3 0f 1e fa b8 a8 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 5d ad 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007fff9cde2488 EFLAGS: 00000202 ORIG_RAX: 00000000000000a8
RAX: ffffffffffffffda RBX: 00007fff9cde3e98 RCX: 00007fab996ac08b
RDX: 0000000000000001 RSI: 0000000000000c00 RDI: 000055bfaf2199b0
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001
R10: 00000000000000bf R11: 0000000000000202 R12: 0000000000000000
R13: 000055bfaf211479 R14: 000055bfaf212b00 R15: 000055bfaf212ad8
</TASK>
irq event stamp: 0
hardirqs last enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<ffffffff81441ab3>] copy_process+0x833/0x32b0
softirqs last enabled at (0): [<ffffffff81441ab3>] copy_process+0x833/0x32b0
softirqs last disabled at (0): [<0000000000000000>] 0x0
Decodeding the stack, I see the following file:lines (against the same
commit as above (74fe02ce122a6103f20))
swap_cluster_assert_empty+0x1b6 mm/swapfile.c:471 WARN: nr == SWAPFILE_CLUSTER && ci->extend_table
__free_cluster+0x2f mm/swapfile.c:585 (return from swap_cluster_assert_empty)
then swap_cluster_free_table at line 586
swap_cache_del_folio+0x120 mm/swap_state.c:298 __swap_cache_del_folio()
(chain __swap_cluster_free_entries → free_cluster → __free_cluster all inlined)
folio_free_swap+0x51b mm/swapfile.c:2037 swap_cache_del_folio(folio)
folio_free_swap+0x2e6 mm/swapfile.c:2034 if (folio_maybe_swapped(folio))
try_to_unuse+0x216d mm/swapfile.c:2628
try_to_unuse+0xbc9 mm/swapfile.c:2592 unuse_mm() chain
__se_sys_swapoff+0x3fb mm/swapfile.c:2903
do_syscall_64+0xfa arch/x86/entry/syscall_64.c
Does it ring a bell?
--breno
next prev parent reply other threads:[~2026-05-11 11:20 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-17 20:06 [PATCH v3 00/12] mm, swap: swap table phase III: remove swap_map Kairui Song via B4 Relay
2026-02-17 20:06 ` [PATCH v3 01/12] mm, swap: protect si->swap_file properly and use as a mount indicator Kairui Song via B4 Relay
2026-02-19 6:36 ` Chris Li
2026-02-17 20:06 ` [PATCH v3 02/12] mm, swap: clean up swapon process and locking Kairui Song via B4 Relay
2026-02-19 6:45 ` Chris Li
2026-02-17 20:06 ` [PATCH v3 03/12] mm, swap: remove redundant arguments and locking for enabling a device Kairui Song via B4 Relay
2026-02-19 6:48 ` Chris Li
2026-02-17 20:06 ` [PATCH v3 04/12] mm, swap: consolidate bad slots setup and make it more robust Kairui Song via B4 Relay
2026-02-19 6:51 ` Chris Li
2026-02-17 20:06 ` [PATCH v3 05/12] mm/workingset: leave highest bits empty for anon shadow Kairui Song via B4 Relay
2026-02-19 6:56 ` Chris Li
2026-02-17 20:06 ` [PATCH v3 06/12] mm, swap: implement helpers for reserving data in the swap table Kairui Song via B4 Relay
2026-02-19 7:00 ` Chris Li
2026-02-17 20:06 ` [PATCH v3 07/12] mm, swap: mark bad slots in swap table directly Kairui Song via B4 Relay
2026-02-19 7:01 ` Chris Li
2026-02-17 20:06 ` [PATCH v3 08/12] mm, swap: simplify swap table sanity range check Kairui Song via B4 Relay
2026-02-19 7:02 ` Chris Li
2026-02-17 20:06 ` [PATCH v3 09/12] mm, swap: use the swap table to track the swap count Kairui Song via B4 Relay
2026-02-18 10:40 ` kernel test robot
2026-02-18 12:22 ` Kairui Song
2026-02-19 7:06 ` Chris Li
2026-05-11 11:19 ` Breno Leitao [this message]
2026-05-11 14:00 ` Kairui Song
2026-02-17 20:06 ` [PATCH v3 10/12] mm, swap: no need to truncate the scan border Kairui Song via B4 Relay
2026-02-19 7:10 ` Chris Li
2026-02-17 20:06 ` [PATCH v3 11/12] mm, swap: simplify checking if a folio is swapped Kairui Song via B4 Relay
2026-02-19 7:18 ` Chris Li
2026-02-17 20:06 ` [PATCH v3 12/12] mm, swap: no need to clear the shadow explicitly Kairui Song via B4 Relay
2026-02-19 7:19 ` Chris Li
2026-02-17 20:10 ` [PATCH v3 00/12] mm, swap: swap table phase III: remove swap_map Kairui Song
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