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Shutemov" To: Matthew Wilcox Cc: linux-mm@kvack.org, kirill.shutemov@linux.intel.com, pasha.tatashin@soleen.com Subject: Re: [PATCH 5/5] mm: Check page poison before finding a head page Message-ID: <20200409142506.7m3kq624q2q7ltwa@box> References: <20200408150148.25290-1-willy@infradead.org> <20200408150148.25290-6-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200408150148.25290-6-willy@infradead.org> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Apr 08, 2020 at 08:01:48AM -0700, Matthew Wilcox wrote: > From: "Matthew Wilcox (Oracle)" > > If a page is poisoned, the page->compound_head will be set to -1. > Since it has bit zero set, we will think it is a tail page, and the head > page is at 0xff..fe. Checking said head page for being poisoned will > not have good results. Therefore we need to check for poison in each > of compound_head(), PageTail() and PageCompound() (and can remove the > checks which are now redundant from the PF_ macros). > > Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Kirill A. Shutemov -- Kirill A. Shutemov