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From: William Kucharski <william.kucharski@oracle.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org
Subject: Re: [PATCH] Assert that pages being written back are locked
Date: Tue, 10 Nov 2020 20:37:19 -0700	[thread overview]
Message-ID: <590D2FE2-1BEF-497D-B572-80F26CDC9CDB@oracle.com> (raw)
In-Reply-To: <20201027224645.GY20115@casper.infradead.org>

Looks good.

Reviewed-by: William Kucharski <william.kucharski@oracle.com>

> On Oct 27, 2020, at 4:46 PM, Matthew Wilcox <willy@infradead.org> wrote:
> 
> From: Matthew Wilcox (Oracle) <willy@infradead.org>
> 
> In write_cache_pages(), we rely on PageLock to prevent writeback from
> starting on locked pages.  I'm not sure if we document anywhere that pages
> that we're starting writes on must be locked, but having an assertion
> will make it clear to users that this is required.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> 
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 3671568d433f..f83dd855594d 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2774,6 +2774,8 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
> 	struct address_space *mapping = page_mapping(page);
> 	int ret, access_ret;
> 
> +	VM_BUG_ON_PGFLAGS(!PageLocked(page), page);
> +
> 	lock_page_memcg(page);
> 	if (mapping && mapping_use_writeback_tags(mapping)) {
> 		XA_STATE(xas, &mapping->i_pages, page_index(page));
> 



      parent reply	other threads:[~2020-11-11  3:37 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-27 22:46 [PATCH] Assert that pages being written back are locked Matthew Wilcox
2020-11-11  0:39 ` Matthew Wilcox
2020-11-11  3:37 ` William Kucharski [this message]

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