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s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=BH51iSUzyg9KZ7syxnXQS3KRs906Uf9wJkKS6a1BsxQ=; b=angZPyAg1GkZnw395mQ1H2hSyZ 8FOuwPttbyu8A1w79GjNbJ2Ieum4ZYQv23Oe3ZuJALNa7bX50chua3/7bvzuk2g4H8GOUuRC6/PQM Hq5J51thoR+VeXDXKg67FA4Pp9G5lzX1rTN9EnLPIxEtzEC9ankHhUyPM0E8SxgpjkNXcMH1Yz4Tt DDw3C28/GiSWV2VPdA5FotyoAThZeYb6ZrknqHo9PTiqk61ys+mhrvVoFqtF28H8htXQUl2cco69T loCYl4Ngxp2H7mit+LkiOZ0FHezZ4vUaS/YRmBAzfLodBDRcJm+pu8DFMhBrYUhI5bzW/qIwD/IRL XBhU3HsQ==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lOhRE-00A7tp-Gh; Tue, 23 Mar 2021 13:51:19 +0000 Date: Tue, 23 Mar 2021 13:51:16 +0000 From: Matthew Wilcox To: David Howells Cc: Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Linus Torvalds , Christoph Hellwig , Alexander Viro , linux-mm@kvack.org, linux-cachefs@redhat.com, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, Jeff Layton , David Wysochanski , linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 02/28] mm: Add an unlock function for PG_private_2/PG_fscache Message-ID: <20210323135116.GF1719932@casper.infradead.org> References: <1885296.1616410586@warthog.procyon.org.uk> <20210321105309.GG3420@casper.infradead.org> <161539526152.286939.8589700175877370401.stgit@warthog.procyon.org.uk> <161539528910.286939.1252328699383291173.stgit@warthog.procyon.org.uk> <2499407.1616505440@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2499407.1616505440@warthog.procyon.org.uk> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: CA649A000841 X-Stat-Signature: wtp41onytixb4z87aiqryfszcrosbpnm Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf15; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616507515-902287 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 Tue, Mar 23, 2021 at 01:17:20PM +0000, David Howells wrote: > +++ b/fs/afs/write.c > @@ -846,7 +846,7 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf) > */ > #ifdef CONFIG_AFS_FSCACHE > if (PageFsCache(page) && > - wait_on_page_bit_killable(page, PG_fscache) < 0) > + wait_on_page_fscache_killable(page) < 0) > return VM_FAULT_RETRY; > #endif > > @@ -861,7 +861,8 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf) > * details the portion of the page we need to write back and we might > * need to redirty the page if there's a problem. > */ > - wait_on_page_writeback(page); > + if (wait_on_page_writeback_killable(page) < 0) > + return VM_FAULT_RETRY | VM_FAULT_LOCKED; You forgot to unlock the page. Also, if you're waiting killably here, do you need to wait before you get the page lock? Ditto for waiting on fscache -- do you want to do that before or after you get the page lock? Also, I never quite understood why you needed to wait for fscache writes to finish before allowing the page to be dirtied. Is this a wait_for_stable_page() kind of situation, where the cache might be calculating a checksum on it? Because as far as I can tell, once the page is dirty in RAM, the contents of the on-disk cache are irrelevant ... unless they're part of a RAID 5 checksum kind of situation. I didn't spot any other problems ...