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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1prrBH-0034Yd-F3; Thu, 27 Apr 2023 02:16:24 +0000 Date: Thu, 27 Apr 2023 03:16:23 +0100 From: Matthew Wilcox To: Doug Anderson Cc: Mel Gorman , Hillf Danton , Andrew Morton , Alexander Viro , Christian Brauner , Linus Torvalds , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Yu Zhao Subject: Re: [PATCH v2 1/4] mm/filemap: Add folio_lock_timeout() Message-ID: References: <20230421151135.v2.1.I2b71e11264c5c214bc59744b9e13e4c353bc5714@changeid> <20230422051858.1696-1-hdanton@sina.com> <20230425010917.1984-1-hdanton@sina.com> <20230426100918.ku32k6mqoogsnijn@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 37FCB160006 X-Stat-Signature: 4168ifd5u1wuj89cmq7gjpq54sngiyc3 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1682561804-73795 X-HE-Meta: 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 9WxB1cgR jsNwA9iwA5z1p0+cxPvJKha5mLo+IXcLGHHIq+6PylIaMAGjs1WNGXaQhT0s5K0Lw+zx0OuCPB7Xb6xnHrilFyyePEZdKjRz3ZrBUiSaf20d3eqJte3JoS66OccNiNJyXbZxqp2oX8VusjqjxltL29OtXHDX5V9TStANN7EUrz/o3d8LUJ5gzyK/Xag== 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 26, 2023 at 02:39:56PM -0700, Doug Anderson wrote: > Sure, I'm happy to do it like you say. Do you have any suggestions for > the similar lock_buffer() case, or are you OK w/ the timeout there? I'd do that similarly, ie: +++ b/mm/migrate.c @@ -691,38 +691,30 @@ EXPORT_SYMBOL(migrate_folio); static bool buffer_migrate_lock_buffers(struct buffer_head *head, enum migrate_mode mode) { - struct buffer_head *bh = head; + struct buffer_head *failed_bh, *bh = head; - /* Simple case, sync compaction */ - if (mode != MIGRATE_ASYNC) { - do { - lock_buffer(bh); - bh = bh->b_this_page; - - } while (bh != head); - - return true; - } - - /* async case, we cannot block on lock_buffer so use trylock_buffer */ do { if (!trylock_buffer(bh)) { - /* - * We failed to lock the buffer and cannot stall in - * async migration. Release the taken locks - */ - struct buffer_head *failed_bh = bh; - bh = head; - while (bh != failed_bh) { - unlock_buffer(bh); - bh = bh->b_this_page; - } - return false; + if (mode == MIGRATE_ASYNC) + goto unlock; + if (mode == MIGRATE_SYNC_LIGHT && !buffer_uptodate(bh)) + goto unlock; + lock_buffer(bh); } bh = bh->b_this_page; } while (bh != head); return true; + +unlock: + /* Failed to lock the buffer and cannot stall */ + failed_bh = bh; + bh = head; + while (bh != failed_bh) { + unlock_buffer(bh); + bh = bh->b_this_page; + } + return false; } static int __buffer_migrate_folio(struct address_space *mapping,