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Wong" , Matthew Wilcox , Mel Gorman Date: Tue, 14 Sep 2021 10:13:04 +1000 Subject: [PATCH 6/6] XFS: remove congestion_wait() loop from xfs_buf_alloc_pages() Cc: linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Message-ID: <163157838440.13293.12568710689057349786.stgit@noble.brown> In-Reply-To: <163157808321.13293.486682642188075090.stgit@noble.brown> References: <163157808321.13293.486682642188075090.stgit@noble.brown> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 313B0D00009D Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=awMekhqm; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b="2y/BbnOY"; dmarc=pass (policy=none) header.from=suse.de; spf=pass (imf15.hostedemail.com: domain of neilb@suse.de designates 195.135.220.28 as permitted sender) smtp.mailfrom=neilb@suse.de X-Stat-Signature: pqwobd8gg6cg5zrnhmakzte9srdjmi97 X-HE-Tag: 1631579322-162649 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: Documentation commment in gfp.h discourages indefinite retry loops on ENOMEM and says of __GFP_NOFAIL that it is definitely preferable to use the flag rather than opencode endless loop around allocator. congestion_wait() is indistinguishable from schedule_timeout_uninterruptible() in practice and it is not a good way to wait for memory to become available. So instead of waiting, allocate a single page using __GFP_NOFAIL, then loop around and try to get any more pages that might be needed with a bulk allocation. This single-page allocation will wait in the most appropriate way. Signed-off-by: NeilBrown --- fs/xfs/xfs_buf.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 5fa6cd947dd4..1ae3768f6504 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -372,8 +372,8 @@ xfs_buf_alloc_pages( /* * Bulk filling of pages can take multiple calls. Not filling the entire - * array is not an allocation failure, so don't back off if we get at - * least one extra page. + * array is not an allocation failure, so don't fail or fall back on + * __GFP_NOFAIL if we get at least one extra page. */ for (;;) { long last = filled; @@ -394,7 +394,7 @@ xfs_buf_alloc_pages( } XFS_STATS_INC(bp->b_mount, xb_page_retries); - congestion_wait(BLK_RW_ASYNC, HZ / 50); + bp->b_pages[filled++] = alloc_page(gfp_mask | __GFP_NOFAIL); } return 0; }