From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kasan-dev@googlegroups.com, Qian Cai <cai@lca.pw>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Matthew Wilcox <willy@infradead.org>,
Mel Gorman <mgorman@techsingularity.net>,
Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH 1/3] mm, page_owner: fix off-by-one error in __set_page_owner_handle()
Date: Thu, 26 Sep 2019 12:09:35 +0300 [thread overview]
Message-ID: <20190926090935.ofbyb2sjhi33nfp3@box> (raw)
In-Reply-To: <20190925143056.25853-2-vbabka@suse.cz>
On Wed, Sep 25, 2019 at 04:30:50PM +0200, Vlastimil Babka wrote:
> As noted by Kirill, commit 7e2f2a0cd17c ("mm, page_owner: record page owner for
> each subpage") has introduced an off-by-one error in __set_page_owner_handle()
> when looking up page_ext for subpages. As a result, the head page page_owner
> info is set twice, while for the last tail page, it's not set at all.
>
> Fix this and also make the code more efficient by advancing the page_ext
> pointer we already have, instead of calling lookup_page_ext() for each subpage.
> Since the full size of struct page_ext is not known at compile time, we can't
> use a simple page_ext++ statement, so introduce a page_ext_next() inline
> function for that.
>
> Reported-by: Kirill A. Shutemov <kirill@shutemov.name>
> Fixes: 7e2f2a0cd17c ("mm, page_owner: record page owner for each subpage")
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
--
Kirill A. Shutemov
next prev parent reply other threads:[~2019-09-26 9:09 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 14:30 [PATCH 0/3] followups to debug_pagealloc improvements through page_owner Vlastimil Babka
2019-09-25 14:30 ` [PATCH 1/3] mm, page_owner: fix off-by-one error in __set_page_owner_handle() Vlastimil Babka
2019-09-26 9:09 ` Kirill A. Shutemov [this message]
2019-09-25 14:30 ` [PATCH 2/3] mm, debug, kasan: save and dump freeing stack trace for kasan Vlastimil Babka
2019-09-26 9:16 ` Kirill A. Shutemov
2019-09-26 9:27 ` Vlastimil Babka
2019-09-25 14:30 ` [PATCH 3/3] mm, page_owner: rename flag indicating that page is allocated Vlastimil Babka
2019-09-26 9:18 ` Kirill A. Shutemov
2019-09-26 9:26 ` Vlastimil Babka
2019-09-25 14:30 ` [PATCH 0/3] followups to debug_pagealloc improvements through page_owner Vlastimil Babka
2019-09-25 14:30 ` [PATCH 1/3] mm, page_owner: fix off-by-one error in __set_page_owner_handle() Vlastimil Babka
2019-09-25 14:30 ` [PATCH 2/3] mm, debug, kasan: save and dump freeing stack trace for kasan Vlastimil Babka
2019-09-25 14:30 ` [PATCH 3/3] mm, page_owner: rename flag indicating that page is allocated Vlastimil Babka
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