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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1ruYr0-00000004dxO-1hXi; Wed, 10 Apr 2024 14:23:10 +0000 Date: Wed, 10 Apr 2024 15:23:10 +0100 From: Matthew Wilcox To: Oscar Salvador Cc: Jane Chu , Miaohe Lin , linux-mm@kvack.org Subject: Re: [PATCH v2 07/11] mm/memory-failure: Convert memory_failure() to use a folio Message-ID: References: <20240408194232.118537-1-willy@infradead.org> <20240408194232.118537-8-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 89A6440011 X-Stat-Signature: kskg8yhe8f55km4euekx8n5by5ei8kzc X-HE-Tag: 1712758994-974647 X-HE-Meta: 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 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: List-Subscribe: List-Unsubscribe: On Wed, Apr 10, 2024 at 12:21:07PM +0200, Oscar Salvador wrote: > On Mon, Apr 08, 2024 at 05:34:29PM -0700, Jane Chu wrote: > > At this stage,  'p' is not expected to be a large page since a _refcount has > > been taken, right?  So is it reasonable to replace the "if (retry)" block > > with a VM_BUG_ON warning?  otherwise, if 'p' became part of a different > > large folio,  how to recover from here ? > > We might have split the THP (if it was part of), but AFAICS > nothing stops the kernel to coallesce this page again into a new THP via e.g: > madvise(MADV_HUGEPAGE) ? Won't that allocate a _new_ THP rather than coalescing in place?