* [PATCH] xfs: fix reclaimed page accounting in xfs_buf_free
@ 2026-08-21 22:03 Eric Sandeen
2026-08-21 23:24 ` Darrick J. Wong
2026-08-24 4:47 ` Christoph Hellwig
0 siblings, 2 replies; 3+ messages in thread
From: Eric Sandeen @ 2026-08-21 22:03 UTC (permalink / raw)
To: linux-xfs@vger.kernel.org; +Cc: Christoph Hellwig
To obtain nr. of pages in "size" bytes, we need howmany(size, PAGE_SIZE)
not howmany(size, PAGE_SHIFT). This over-reports reclaim by orders of
magnitude, up to 4096x on a 64k page system.
Fixes: e2874632a621 ("xfs: use vmalloc instead of vm_map_area for buffer backing memory")
Cc: stable@vger.kernel.org # v6.15+
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---
fs/xfs/xfs_buf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 1a5340baeabf..8256c1d13ce2 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -139,7 +139,7 @@ xfs_buf_free(
ASSERT(list_empty(&bp->b_lru));
if (!xfs_buftarg_is_mem(bp->b_target) && size >= PAGE_SIZE)
- mm_account_reclaimed_pages(howmany(size, PAGE_SHIFT));
+ mm_account_reclaimed_pages(howmany(size, PAGE_SIZE));
if (is_vmalloc_addr(bp->b_addr))
vfree(bp->b_addr);
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] xfs: fix reclaimed page accounting in xfs_buf_free
2026-08-21 22:03 [PATCH] xfs: fix reclaimed page accounting in xfs_buf_free Eric Sandeen
@ 2026-08-21 23:24 ` Darrick J. Wong
2026-08-24 4:47 ` Christoph Hellwig
1 sibling, 0 replies; 3+ messages in thread
From: Darrick J. Wong @ 2026-08-21 23:24 UTC (permalink / raw)
To: Eric Sandeen; +Cc: linux-xfs@vger.kernel.org, Christoph Hellwig
On Fri, Aug 21, 2026 at 05:03:37PM -0500, Eric Sandeen wrote:
> To obtain nr. of pages in "size" bytes, we need howmany(size, PAGE_SIZE)
> not howmany(size, PAGE_SHIFT). This over-reports reclaim by orders of
> magnitude, up to 4096x on a 64k page system.
>
> Fixes: e2874632a621 ("xfs: use vmalloc instead of vm_map_area for buffer backing memory")
> Cc: stable@vger.kernel.org # v6.15+
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Yikes.
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
--D
> ---
> fs/xfs/xfs_buf.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index 1a5340baeabf..8256c1d13ce2 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -139,7 +139,7 @@ xfs_buf_free(
> ASSERT(list_empty(&bp->b_lru));
>
> if (!xfs_buftarg_is_mem(bp->b_target) && size >= PAGE_SIZE)
> - mm_account_reclaimed_pages(howmany(size, PAGE_SHIFT));
> + mm_account_reclaimed_pages(howmany(size, PAGE_SIZE));
>
> if (is_vmalloc_addr(bp->b_addr))
> vfree(bp->b_addr);
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] xfs: fix reclaimed page accounting in xfs_buf_free
2026-08-21 22:03 [PATCH] xfs: fix reclaimed page accounting in xfs_buf_free Eric Sandeen
2026-08-21 23:24 ` Darrick J. Wong
@ 2026-08-24 4:47 ` Christoph Hellwig
1 sibling, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2026-08-24 4:47 UTC (permalink / raw)
To: Eric Sandeen; +Cc: linux-xfs@vger.kernel.org, Christoph Hellwig
On Fri, Aug 21, 2026 at 05:03:37PM -0500, Eric Sandeen wrote:
> To obtain nr. of pages in "size" bytes, we need howmany(size, PAGE_SIZE)
> not howmany(size, PAGE_SHIFT). This over-reports reclaim by orders of
> magnitude, up to 4096x on a 64k page system.
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-08-21 23:24 ` Darrick J. Wong
2026-08-24 4:47 ` Christoph Hellwig
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