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Message-ID: <20190821014858.GA9158@infradead.org> References: <20190817074439.84C6C1056A3@localhost.localdomain> <20190819174600.GN24086@twin.jikos.cz> <20190820023031.GC9594@infradead.org> <6f99b73c-db8f-8135-b827-0a135734d7da@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6f99b73c-db8f-8135-b827-0a135734d7da@suse.cz> User-Agent: Mutt/1.11.4 (2019-03-13) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: erhard_f@mailbox.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dave Chinner , Josef Bacik , stable@vger.kernel.org, dsterba@suse.cz, Christoph Hellwig , Chris Mason , David Sterba , Andrew Morton , linuxppc-dev@lists.ozlabs.org, linux-btrfs@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Aug 20, 2019 at 01:06:25PM +0200, Vlastimil Babka wrote: > > The whole point of copy_page is to copy exactly one page and it makes > > sense to assume that is aligned. A sane memcpy would use the same > > underlying primitives as well after checking they fit. So I think the > > prime issue here is btrfs' use of copy_page instead of memcpy. The > > secondary issue is slub fucking up alignments for no good reason. We > > just got bitten by that crap again in XFS as well :( > > Meh, I should finally get back to https://lwn.net/Articles/787740/ right Yes. For now Dave came up with an idea for a workaround that will be forward-compatible with that: https://www.spinics.net/lists/linux-xfs/msg30521.html