* [PATCH] mm: Assert the folio is locked in folio_start_writeback()
@ 2025-02-26 15:36 Matthew Wilcox (Oracle)
2025-02-26 16:21 ` Darrick J. Wong
0 siblings, 1 reply; 2+ messages in thread
From: Matthew Wilcox (Oracle) @ 2025-02-26 15:36 UTC (permalink / raw)
To: Andrew Morton; +Cc: Matthew Wilcox (Oracle), linux-mm, linux-fsdevel
The folio must be locked when we start writeback in order to
prevent writeback from being started twice on the same folio.
I don't expect this to catch any problems, but it should be
good documentation.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
mm/page-writeback.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index eb55ece39c56..8b325aa525eb 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -3109,6 +3109,7 @@ void __folio_start_writeback(struct folio *folio, bool keep_write)
int access_ret;
VM_BUG_ON_FOLIO(folio_test_writeback(folio), folio);
+ VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
if (mapping && mapping_use_writeback_tags(mapping)) {
XA_STATE(xas, &mapping->i_pages, folio_index(folio));
--
2.47.2
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [PATCH] mm: Assert the folio is locked in folio_start_writeback()
2025-02-26 15:36 [PATCH] mm: Assert the folio is locked in folio_start_writeback() Matthew Wilcox (Oracle)
@ 2025-02-26 16:21 ` Darrick J. Wong
0 siblings, 0 replies; 2+ messages in thread
From: Darrick J. Wong @ 2025-02-26 16:21 UTC (permalink / raw)
To: Matthew Wilcox (Oracle); +Cc: Andrew Morton, linux-mm, linux-fsdevel
On Wed, Feb 26, 2025 at 03:36:12PM +0000, Matthew Wilcox (Oracle) wrote:
> The folio must be locked when we start writeback in order to
> prevent writeback from being started twice on the same folio.
> I don't expect this to catch any problems, but it should be
> good documentation.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
LGTM
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
--D
> ---
> mm/page-writeback.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index eb55ece39c56..8b325aa525eb 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -3109,6 +3109,7 @@ void __folio_start_writeback(struct folio *folio, bool keep_write)
> int access_ret;
>
> VM_BUG_ON_FOLIO(folio_test_writeback(folio), folio);
> + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
>
> if (mapping && mapping_use_writeback_tags(mapping)) {
> XA_STATE(xas, &mapping->i_pages, folio_index(folio));
> --
> 2.47.2
>
>
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2025-02-26 15:36 [PATCH] mm: Assert the folio is locked in folio_start_writeback() Matthew Wilcox (Oracle)
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