This is a note to let you know that I've just added the patch titled
mm: zswap: fix writeback shinker GFP_NOIO/GFP_NOFS recursion
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-zswap-fix-writeback-shinker-gfp_noio-gfp_nofs-recursion.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 30fb6a8d9e3378919f378f9bf561142b4a6d2637 Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Date: Thu, 21 Mar 2024 14:25:32 -0400
Subject: mm: zswap: fix writeback shinker GFP_NOIO/GFP_NOFS recursion
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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From: Johannes Weiner <hannes@xxxxxxxxxxx>
commit 30fb6a8d9e3378919f378f9bf561142b4a6d2637 upstream.
Kent forwards this bug report of zswap re-entering the block layer
from an IO request allocation and locking up:
[10264.128242] sysrq: Show Blocked State
[10264.128268] task:kworker/20:0H state:D stack:0 pid:143 tgid:143 ppid:2 flags:0x00004000
[10264.128271] Workqueue: bcachefs_io btree_write_submit [bcachefs]
[10264.128295] Call Trace:
[10264.128295] <TASK>
[10264.128297] __schedule+0x3e6/0x1520
[10264.128303] schedule+0x32/0xd0
[10264.128304] schedule_timeout+0x98/0x160
[10264.128308] io_schedule_timeout+0x50/0x80
[10264.128309] wait_for_completion_io_timeout+0x7f/0x180
[10264.128310] submit_bio_wait+0x78/0xb0
[10264.128313] swap_writepage_bdev_sync+0xf6/0x150
[10264.128317] zswap_writeback_entry+0xf2/0x180
[10264.128319] shrink_memcg_cb+0xe7/0x2f0
[10264.128322] __list_lru_walk_one+0xb9/0x1d0
[10264.128325] list_lru_walk_one+0x5d/0x90
[10264.128326] zswap_shrinker_scan+0xc4/0x130
[10264.128327] do_shrink_slab+0x13f/0x360
[10264.128328] shrink_slab+0x28e/0x3c0
[10264.128329] shrink_one+0x123/0x1b0
[10264.128331] shrink_node+0x97e/0xbc0
[10264.128332] do_try_to_free_pages+0xe7/0x5b0
[10264.128333] try_to_free_pages+0xe1/0x200
[10264.128334] __alloc_pages_slowpath.constprop.0+0x343/0xde0
[10264.128337] __alloc_pages+0x32d/0x350
[10264.128338] allocate_slab+0x400/0x460
[10264.128339] ___slab_alloc+0x40d/0xa40
[10264.128345] kmem_cache_alloc+0x2e7/0x330
[10264.128348] mempool_alloc+0x86/0x1b0
[10264.128349] bio_alloc_bioset+0x200/0x4f0
[10264.128352] bio_alloc_clone+0x23/0x60
[10264.128354] alloc_io+0x26/0xf0 [dm_mod 7e9e6b44df4927f93fb3e4b5c782767396f58382]
[10264.128361] dm_submit_bio+0xb8/0x580 [dm_mod 7e9e6b44df4927f93fb3e4b5c782767396f58382]
[10264.128366] __submit_bio+0xb0/0x170
[10264.128367] submit_bio_noacct_nocheck+0x159/0x370
[10264.128368] bch2_submit_wbio_replicas+0x21c/0x3a0 [bcachefs 85f1b9a7a824f272eff794653a06dde1a94439f2]
[10264.128391] btree_write_submit+0x1cf/0x220 [bcachefs 85f1b9a7a824f272eff794653a06dde1a94439f2]
[10264.128406] process_one_work+0x178/0x350
[10264.128408] worker_thread+0x30f/0x450
[10264.128409] kthread+0xe5/0x120
The zswap shrinker resumes the swap_writepage()s that were intercepted
by the zswap store. This will enter the block layer, and may even
enter the filesystem depending on the swap backing file.
Make it respect GFP_NOIO and GFP_NOFS.
Link: https://lore.kernel.org/linux-mm/rc4pk2r42oyvjo4dc62z6sovquyllq56i5cdgcaqbd7wy3hfzr@n4nbxido3fme/
Link: https://lkml.kernel.org/r/20240321182532.60000-1-hannes@xxxxxxxxxxx
Fixes: b5ba474f3f51 ("zswap: shrink zswap pool based on memory pressure")
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reported-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Acked-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Reported-by: Jérôme Poulin <jeromepoulin@xxxxxxxxx>
Reviewed-by: Nhat Pham <nphamcs@xxxxxxxxx>
Reviewed-by: Chengming Zhou <chengming.zhou@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx [v6.8]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/zswap.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -645,6 +645,14 @@ static unsigned long zswap_shrinker_coun
if (!zswap_shrinker_enabled || !mem_cgroup_zswap_writeback_enabled(memcg))
return 0;
+ /*
+ * The shrinker resumes swap writeback, which will enter block
+ * and may enter fs. XXX: Harmonize with vmscan.c __GFP_FS
+ * rules (may_enter_fs()), which apply on a per-folio basis.
+ */
+ if (!gfp_has_io_fs(sc->gfp_mask))
+ return 0;
+
#ifdef CONFIG_MEMCG_KMEM
mem_cgroup_flush_stats(memcg);
nr_backing = memcg_page_state(memcg, MEMCG_ZSWAP_B) >> PAGE_SHIFT;
Patches currently in stable-queue which might be from hannes@xxxxxxxxxxx are
queue-6.8/mm-zswap-fix-writeback-shinker-gfp_noio-gfp_nofs-recursion.patch
