The patch titled
Subject: zswap: don't warn if none swapcache folio is passed to zswap_load
has been added to the -mm mm-unstable branch. Its filename is
zswap-make-zswap_load-take-a-folio-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zswap-make-zswap_load-take-a-folio-fix.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Subject: zswap: don't warn if none swapcache folio is passed to zswap_load
Date: Thu, 10 Aug 2023 17:56:52 +0800
With mm-unstable branch, if trigger swap activity and it's possible
see following warning:
[ 178.093511][ T651] WARNING: CPU: 2 PID: 651 at mm/zswap.c:1387 zswap_load+0x67/0x570
[ 178.095155][ T651] Modules linked in:
[ 178.096103][ T651] CPU: 2 PID: 651 Comm: gmain Not tainted 6.5.0-rc4-00492-gad3232df3e41 #148
[ 178.098372][ T651] Hardware name: QEMU Standard PC (i440FX + PIIX,1996), BIOS 1.14.0-2 04/01/2014
[ 178.101114][ T651] RIP: 0010:zswap_load+0x67/0x570
[ 178.102359][ T651] Code: a0 78 4b 85 e8 ea db ff ff 48 8b 00 a8 01 0f 84 84 04 00 00 48 89 df e8 d7 db ff ff 48 8b 00 a9 00 00 08 00 0f 85 c4
[ 178.106376][ T651] RSP: 0018:ffffc900011b3760 EFLAGS: 00010246
[ 178.107675][ T651] RAX: 0017ffffc0080001 RBX: ffffea0004a991c0 RCX:ffffc900011b37dc
[ 178.109242][ T651] RDX: 0000000000000000 RSI: 0000000000000001 RDI:ffffea0004a991c0
[ 178.110916][ T651] RBP: ffffea0004a991c0 R08: 0000000000000243 R09:00000000c9a1aafc
[ 178.112377][ T651] R10: 00000000c9657db3 R11: 000000003c9657db R12:0000000000014b9c
[ 178.113698][ T651] R13: ffff88813501e710 R14: ffff88810d591000 R15:0000000000000000
[ 178.115008][ T651] FS: 00007fb21a9ff700(0000) GS:ffff88813bc80000(0000) knlGS:0000000000000000
[ 178.116423][ T651] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 178.117421][ T651] CR2: 00005632cbfc81f6 CR3: 0000000131450002 CR4:0000000000370ee0
[ 178.118683][ T651] DR0: 0000000000000000 DR1: 0000000000000000 DR2:0000000000000000
[ 178.119894][ T651] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:0000000000000400
[ 178.121087][ T651] Call Trace:
[ 178.121654][ T651] <TASK>
[ 178.122109][ T651] ? zswap_load+0x67/0x570
[ 178.122658][ T651] ? __warn+0x81/0x170
[ 178.123119][ T651] ? zswap_load+0x67/0x570
[ 178.123608][ T651] ? report_bug+0x167/0x190
[ 178.124150][ T651] ? handle_bug+0x3c/0x70
[ 178.124615][ T651] ? exc_invalid_op+0x13/0x60
[ 178.125192][ T651] ? asm_exc_invalid_op+0x16/0x20
[ 178.125753][ T651] ? zswap_load+0x67/0x570
[ 178.126231][ T651] ? lock_acquire+0xbb/0x290
[ 178.126745][ T651] ? folio_add_lru+0x40/0x1c0
[ 178.127261][ T651] ? find_held_lock+0x2b/0x80
[ 178.127776][ T651] swap_readpage+0xc7/0x5c0
[ 178.128273][ T651] do_swap_page+0x86d/0xf50
[ 178.128770][ T651] ? __pte_offset_map+0x3e/0x290
[ 178.129321][ T651] ? __pte_offset_map+0x1c4/0x290
[ 178.129883][ T651] __handle_mm_fault+0x6ad/0xca0
[ 178.130419][ T651] handle_mm_fault+0x18b/0x410
[ 178.130992][ T651] do_user_addr_fault+0x1f1/0x820
[ 178.132076][ T651] exc_page_fault+0x63/0x1a0
[ 178.132599][ T651] asm_exc_page_fault+0x22/0x30
It's possible that swap_readpage() is called with none swapcache folio
in do_swap_page() and trigger this warning. So we shouldn't assume
zswap_load() always takes swapcache folio.
Link: https://lkml.kernel.org/r/20230810095652.3905184-1-fengwei.yin@xxxxxxxxx
Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zswap.c | 1 -
1 file changed, 1 deletion(-)
--- a/mm/zswap.c~zswap-make-zswap_load-take-a-folio-fix
+++ a/mm/zswap.c
@@ -1421,7 +1421,6 @@ bool zswap_load(struct folio *folio)
bool ret;
VM_WARN_ON_ONCE(!folio_test_locked(folio));
- VM_WARN_ON_ONCE(!folio_test_swapcache(folio));
/* find */
spin_lock(&tree->lock);
_
Patches currently in -mm which might be from fengwei.yin@xxxxxxxxx are
madvise-madvise_cold_or_pageout_pte_range-dont-use-mapcount-against-large-folio-for-sharing-check.patch
madvise-madvise_free_huge_pmd-dont-use-mapcount-against-large-folio-for-sharing-check.patch
madvise-madvise_free_pte_range-dont-use-mapcount-against-large-folio-for-sharing-check.patch
zswap-make-zswap_load-take-a-folio-fix.patch
filemap-add-filemap_map_folio_range.patch
rmap-add-folio_add_file_rmap_range.patch
mm-convert-do_set_pte-to-set_pte_range.patch
filemap-batch-pte-mappings.patch
