From: Barry Song <baohua@kernel.org>
To: David Carlier <devnexen@gmail.com>
Cc: Kairui Song <kasong@tencent.com>,
David Hildenbrand <david@kernel.org>,
Chris Li <chrisl@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Kemeng Shi <shikemeng@huaweicloud.com>,
Nhat Pham <nphamcs@gmail.com>, Baoquan He <bhe@redhat.com>,
Youngjun Park <youngjun.park@lge.com>,
NeilBrown <neil@brown.name>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v3] mm/page_io: use sio->len for PSWPIN accounting in sio_read_complete()
Date: Thu, 2 Apr 2026 07:43:09 +0800 [thread overview]
Message-ID: <CAGsJ_4xbz62bSVggPdwrELBphto2ZX=OViw2o=ighdY9JhJ_bg@mail.gmail.com> (raw)
In-Reply-To: <20260401074753.238053-1-devnexen@gmail.com>
On Wed, Apr 1, 2026 at 3:47 PM David Carlier <devnexen@gmail.com> wrote:
>
> sio_read_complete() uses sio->pages to account global PSWPIN vm events,
> but sio->pages tracks the number of bvec entries (folios), not base
> pages.
>
> While large folios cannot currently reach this path (SWP_FS_OPS and
> SWP_SYNCHRONOUS_IO are mutually exclusive, and mTHP swap-in allocation
> is gated on SWP_SYNCHRONOUS_IO), the accounting is semantically
> inconsistent with the per-memcg path which correctly uses
> folio_nr_pages().
>
> Use sio->len >> PAGE_SHIFT instead, which gives the correct base page
> count since sio->len is accumulated via folio_size(folio).
>
> Signed-off-by: David Carlier <devnexen@gmail.com>
LGTM,
Reviewed-by: Barry Song <baohua@kernel.org>
next prev parent reply other threads:[~2026-04-01 23:43 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-30 7:12 [PATCH v2] mm/page_io: fix PSWPIN undercount for large folios " David Carlier
2026-03-30 22:20 ` Andrew Morton
2026-03-31 22:33 ` Barry Song
2026-04-01 7:10 ` David CARLIER
2026-04-01 7:30 ` David Hildenbrand (Arm)
2026-04-01 20:22 ` Barry Song
2026-04-01 7:47 ` [PATCH v3] mm/page_io: use sio->len for PSWPIN accounting " David Carlier
2026-04-01 8:32 ` David Hildenbrand (Arm)
2026-04-01 22:58 ` Andrew Morton
2026-04-01 23:43 ` Barry Song [this message]
2026-04-02 3:07 ` Chris Li
2026-04-02 4:11 ` Matthew Wilcox
2026-04-02 5:51 ` Barry Song
2026-04-02 6:01 ` David CARLIER
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