From: Greg KH <gregkh@linuxfoundation.org>
To: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Kanchana P Sridhar <kanchana.p.sridhar@intel.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Yosry Ahmed <yosryahmed@google.com>,
Nhat Pham <nphamcs@gmail.com>,
Chengming Zhou <chengming.zhou@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, stable@vger.kernel.org
Subject: Re: [PATCH v6.12 hotfix] mm/zswap: fix inconsistent charging when zswap_store_page() fails
Date: Tue, 28 Jan 2025 10:13:58 +0100 [thread overview]
Message-ID: <2025012842-rebuilt-snugly-518f@gregkh> (raw)
In-Reply-To: <20250128174938.2638-1-42.hyeyoo@gmail.com>
On Wed, Jan 29, 2025 at 02:49:38AM +0900, Hyeonggon Yoo wrote:
> Commit b7c0ccdfbafd ("mm: zswap: support large folios in zswap_store()")
> mistakenly skipped charging any zswapped pages when a single call to
> zswap_store_page() failed, even if some pages in the folio are
> successfully stored in zswap.
>
> Making things worse, these not-charged pages are uncharged in
> zswap_entry_free(), making zswap charging inconsistent.
>
> This inconsistency triggers two warnings when following these steps:
> # On a machine with 64GiB of RAM and 36GiB of zswap
> $ stress-ng --bigheap 2 # wait until the OOM-killer kills stress-ng
> $ sudo reboot
>
> Two warnings are:
> in mm/memcontrol.c:163, function obj_cgroup_release():
> WARN_ON_ONCE(nr_bytes & (PAGE_SIZE - 1));
>
> in mm/page_counter.c:60, function page_counter_cancel():
> if (WARN_ONCE(new < 0, "page_counter underflow: %ld nr_pages=%lu\n",
> new, nr_pages))
>
> Charge zswapped pages even if some pages of the folio are not zswapped.
> After resolving the inconsistency, these warnings disappear.
>
> Fixes: b7c0ccdfbafd ("mm: zswap: support large folios in zswap_store()")
This commit is in 6.13, not 6.12, so your subject line is a bit
confusing :(
next prev parent reply other threads:[~2025-01-28 9:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-28 17:49 Hyeonggon Yoo
2025-01-28 9:13 ` Greg KH [this message]
2025-01-28 18:18 ` Hyeonggon Yoo
2025-01-28 9:42 ` Vlastimil Babka
2025-01-28 19:05 ` Hyeonggon Yoo
2025-01-28 17:53 ` Hyeonggon Yoo
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