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Thu, 29 May 2025 21:31:22 -0400 X-MC-Unique: -yCsk8RrONOypx7wt6dRkA-1 X-Mimecast-MFC-AGG-ID: -yCsk8RrONOypx7wt6dRkA_1748568681 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BB45F180087F; Fri, 30 May 2025 01:31:20 +0000 (UTC) Received: from localhost (unknown [10.72.112.13]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5BDB2180047F; Fri, 30 May 2025 01:31:18 +0000 (UTC) Date: Fri, 30 May 2025 09:31:08 +0800 From: Baoquan He To: Kemeng Shi Cc: akpm@linux-foundation.org, kasong@tencent.com, hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/4] mm: swap: move nr_swap_pages counter decrement from folio_alloc_swap() to swap_range_alloc() Message-ID: References: <20250522122554.12209-1-shikemeng@huaweicloud.com> <20250522122554.12209-2-shikemeng@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250522122554.12209-2-shikemeng@huaweicloud.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Rspam-User: X-Rspamd-Queue-Id: D07DB14000C X-Rspamd-Server: rspam09 X-Stat-Signature: ndmboyigufpaypi7nznrc77qerh5hy1u X-HE-Tag: 1748568688-973564 X-HE-Meta: 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 7Z6clCTW 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05/22/25 at 08:25pm, Kemeng Shi wrote: > When folio_alloc_swap() encounters a failure in either > mem_cgroup_try_charge_swap() or add_to_swap_cache(), nr_swap_pages counter > is not decremented for allocated entry. However, the following > put_swap_folio() will increase nr_swap_pages counter unpairly and lead to > an imbalance. > > Move nr_swap_pages decrement from folio_alloc_swap() to swap_range_alloc() > to pair the nr_swap_pages counting. > > Fixes: 0ff67f990bd45 ("mm, swap: remove swap slot cache") > Signed-off-by: Kemeng Shi > --- > mm/swapfile.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) LGTM, Reviewed-by: Baoquan He > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 026090bf3efe..75b69213c2e7 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1115,6 +1115,7 @@ static void swap_range_alloc(struct swap_info_struct *si, > if (vm_swap_full()) > schedule_work(&si->reclaim_work); > } > + atomic_long_sub(nr_entries, &nr_swap_pages); > } > > static void swap_range_free(struct swap_info_struct *si, unsigned long offset, > @@ -1313,7 +1314,6 @@ int folio_alloc_swap(struct folio *folio, gfp_t gfp) > if (add_to_swap_cache(folio, entry, gfp | __GFP_NOMEMALLOC, NULL)) > goto out_free; > > - atomic_long_sub(size, &nr_swap_pages); > return 0; > > out_free: > -- > 2.30.0 >