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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pPFB1-00HQxz-L9; Tue, 07 Feb 2023 04:01:51 +0000 Date: Tue, 7 Feb 2023 04:01:51 +0000 From: Matthew Wilcox To: Luis Chamberlain Cc: hughd@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, p.raghav@samsung.com, dave@stgolabs.net, a.manzanares@samsung.com, linux-kernel@vger.kernel.org Subject: Re: [RFC 2/2] shmem: add support to ignore swap Message-ID: References: <20230207025259.2522793-1-mcgrof@kernel.org> <20230207025259.2522793-3-mcgrof@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230207025259.2522793-3-mcgrof@kernel.org> X-Rspamd-Queue-Id: 64AF21C0009 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 4xoiqff5n6gt89xz46kd79if8fodtzt1 X-HE-Tag: 1675742518-444526 X-HE-Meta: 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 7tbRfJa0 CaqirgmNRkx6uExiBI+zGMCXaAnJCw/LACqFO7A1FM1VtNFVAn7pKEn3C3Rs1lQcV0Jt4W9PAaOJdWAQ5e13BbwiO0t4c2EpAR8fMZhnBmj1lJs1ZcBJlcXkI6huLAlJeJd5GXQIS7ZtqvWptn76LwLrBWA== 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 Mon, Feb 06, 2023 at 06:52:59PM -0800, Luis Chamberlain wrote: > @@ -1334,11 +1336,15 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) > struct shmem_inode_info *info; > struct address_space *mapping = folio->mapping; > struct inode *inode = mapping->host; > + struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); > swp_entry_t swap; > pgoff_t index; > > BUG_ON(!folio_test_locked(folio)); > > + if (wbc->for_reclaim && unlikely(sbinfo->noswap)) > + return AOP_WRITEPAGE_ACTIVATE; Not sure this is the best way to handle this. We'll still incur the oevrhead of tracking shmem pages on the LRU, only to fail to write them out when the VM thinks we should get rid of them. We'd be better off not putting them on the LRU in the first place.