From patchwork Tue Sep 14 00:13:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12491095 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 914D8C433EF for ; Tue, 14 Sep 2021 00:27:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4D16E60F4C for ; Tue, 14 Sep 2021 00:27:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 4D16E60F4C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id D70D2940007; Mon, 13 Sep 2021 20:27:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D1FC46B0071; Mon, 13 Sep 2021 20:27:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C0EC4940007; Mon, 13 Sep 2021 20:27:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0218.hostedemail.com [216.40.44.218]) by kanga.kvack.org (Postfix) with ESMTP id B45786B006C for ; Mon, 13 Sep 2021 20:27:51 -0400 (EDT) Received: from smtpin32.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 7601718182898 for ; Tue, 14 Sep 2021 00:27:51 +0000 (UTC) X-FDA: 78584291142.32.9053B75 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf24.hostedemail.com (Postfix) with ESMTP id 1BE86B000099 for ; Tue, 14 Sep 2021 00:27:51 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 293F9200AB; Tue, 14 Sep 2021 00:27:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1631579270; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=g0SHCABpDWS99bZKx2dAHZNwjxnp06aPgrFMV26MaeI=; b=vKluE2nOK+k9zSBiBmELjziS/Je3Eb7ExMrDxZnQgF+C9Jlx6UUT2UchNrxrTG4opSHW5e CKXutZ33ekHMt2YOaXMYX4apmr9T8sIP9VrAD8dS5JEAhAtmV0vAgHwumYWtDsneQYQkTB UeLE85Mise3J1lrnNfUn35emK0UMcjc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1631579270; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=g0SHCABpDWS99bZKx2dAHZNwjxnp06aPgrFMV26MaeI=; b=KHVFdZ4dzTCRc/u9v2yXF/btQQFh1qUTgYDrabeG0U2Emc2V42uJV6/y0HDLdM8r95xM8U VRa1YzY4Iys9V4AQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id BDB7613ADE; Tue, 14 Sep 2021 00:27:46 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id Ja8IH4LsP2EUawAAMHmgww (envelope-from ); Tue, 14 Sep 2021 00:27:46 +0000 From: NeilBrown To: Andrew Morton , Theodore Ts'o , Andreas Dilger , "Darrick J. Wong" , Matthew Wilcox , Mel Gorman Date: Tue, 14 Sep 2021 10:13:04 +1000 Subject: [PATCH 1/6] MM: improve documentation for __GFP_NOFAIL 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: <163157838436.13293.8832201267053160346.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-Stat-Signature: chfbk3qowqde1nxwj9ysjfphtr18xfex Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=vKluE2nO; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=KHVFdZ4d; dmarc=pass (policy=none) header.from=suse.de; spf=pass (imf24.hostedemail.com: domain of neilb@suse.de designates 195.135.220.29 as permitted sender) smtp.mailfrom=neilb@suse.de X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 1BE86B000099 X-HE-Tag: 1631579271-118868 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: __GFP_NOFAIL is documented both in gfp.h and memory-allocation.rst. The details are not entirely consistent. This patch ensures both places state that: - there is a cost potentially imposed on other subsystems - it should only be used when there is no real alternative - it is preferable to an endless loop - it is strongly discourages for costly-order allocations. Signed-off-by: NeilBrown Acked-by: Michal Hocko --- Documentation/core-api/memory-allocation.rst | 9 ++++++++- include/linux/gfp.h | 4 ++++ 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/Documentation/core-api/memory-allocation.rst b/Documentation/core-api/memory-allocation.rst index 5954ddf6ee13..9458ce72d31c 100644 --- a/Documentation/core-api/memory-allocation.rst +++ b/Documentation/core-api/memory-allocation.rst @@ -126,7 +126,14 @@ or another request. * ``GFP_KERNEL | __GFP_NOFAIL`` - overrides the default allocator behavior and all allocation requests will loop endlessly until they succeed. - This might be really dangerous especially for larger orders. + The allocator may provide access to memory that would otherwise be + reserved in order to satisfy this allocation which might adversely + affect other subsystems. So it should only be used when there is no + reasonable failure policy and when the memory is likely to be freed + again in the near future. Its use is strong discourage (via a + WARN_ON) for allocations larger than ``PAGE_ALLOC_COSTLY_ORDER``. + While this flag is best avoided, it is still preferable to endless + loops around the allocator. Selecting memory allocator ========================== diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 55b2ec1f965a..101479373738 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -209,6 +209,10 @@ struct vm_area_struct; * used only when there is no reasonable failure policy) but it is * definitely preferable to use the flag rather than opencode endless * loop around allocator. + * Use of this flag may provide access to memory which would otherwise be + * reserved. As such it must be understood that there can be a cost imposed + * on other subsystems as well as the obvious cost of placing the calling + * thread in an uninterruptible indefinite wait. * Using this flag for costly allocations is _highly_ discouraged. */ #define __GFP_IO ((__force gfp_t)___GFP_IO) From patchwork Tue Sep 14 00:13:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12491097 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92889C433FE for ; Tue, 14 Sep 2021 00:28:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0CADF6112E for ; Tue, 14 Sep 2021 00:28:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0CADF6112E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id AD833940008; Mon, 13 Sep 2021 20:28:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A87A56B0071; Mon, 13 Sep 2021 20:28:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 97707940008; Mon, 13 Sep 2021 20:28:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0251.hostedemail.com [216.40.44.251]) by kanga.kvack.org (Postfix) with ESMTP id 8B1336B006C for ; Mon, 13 Sep 2021 20:28:02 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 3CAA68249980 for ; Tue, 14 Sep 2021 00:28:02 +0000 (UTC) X-FDA: 78584291604.10.AE8346E Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf15.hostedemail.com (Postfix) with ESMTP id DC2F1D000099 for ; Tue, 14 Sep 2021 00:28:01 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 94D4E200AA; Tue, 14 Sep 2021 00:28:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1631579280; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fz478wuK2aqSUdVMTm0N58JnzuLLXcDfeQcH+i0TRAc=; b=xe9UJcFJ9/etWuZVpkedbCfZdZGh4I+9k/xRiVFR+eOLjUc/38MzmSICzhxCaBDieHWCCU IGfVi+k1JTkaS1tbSmYAM2N1g3fFIk1xYp+Z9Ww/PkVOo0+PW5yrER7llpNQuvMk4su7zT Bx3yl4AFRjURJB8UHQZi0ijxP89K9dA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1631579280; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fz478wuK2aqSUdVMTm0N58JnzuLLXcDfeQcH+i0TRAc=; b=Z5hLlNcuwJJinzCF56fW+4/hhbShZz4exvm5VcH5q6dN4x9juqo28ZwRLP51q89RkWh1Kh Pld6ww2EgjdayQDQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 386E713ADE; Tue, 14 Sep 2021 00:27:56 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 5x0MOozsP2EiawAAMHmgww (envelope-from ); Tue, 14 Sep 2021 00:27:56 +0000 From: NeilBrown To: Andrew Morton , Theodore Ts'o , Andreas Dilger , "Darrick J. Wong" , Matthew Wilcox , Mel Gorman Date: Tue, 14 Sep 2021 10:13:04 +1000 Subject: [PATCH 2/6] MM: annotate congestion_wait() and wait_iff_congested() as ineffective. 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: <163157838437.13293.15392955714346973750.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 Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=xe9UJcFJ; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=Z5hLlNcu; spf=pass (imf15.hostedemail.com: domain of neilb@suse.de designates 195.135.220.29 as permitted sender) smtp.mailfrom=neilb@suse.de; dmarc=pass (policy=none) header.from=suse.de X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: DC2F1D000099 X-Stat-Signature: b49gyxtnf84xdf6c7thw5mhndueng94j X-HE-Tag: 1631579281-295247 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: Only 4 subsystems call set_bdi_congested() or clear_bdi_congested(): block/pktcdvd, fs/ceph fs/fuse fs/nfs It may make sense to use congestion_wait() or wait_iff_congested() within these subsystems, but they have no value outside of these. Add documentation comments to these functions to discourage further use. Signed-off-by: NeilBrown --- include/linux/backing-dev.h | 7 +++++++ mm/backing-dev.c | 9 +++++++++ 2 files changed, 16 insertions(+) diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index ac7f231b8825..cc9513840351 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -153,6 +153,13 @@ static inline int wb_congested(struct bdi_writeback *wb, int cong_bits) return wb->congested & cong_bits; } +/* NOTE congestion_wait() and wait_iff_congested() are + * largely useless except as documentation. + * congestion_wait() will (almost) always wait for the given timeout. + * wait_iff_congested() will (almost) never wait, but will call + * cond_resched(). + * Were possible an alternative waiting strategy should be found. + */ long congestion_wait(int sync, long timeout); long wait_iff_congested(int sync, long timeout); diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 4a9d4e27d0d9..53472ab38796 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -1023,6 +1023,11 @@ EXPORT_SYMBOL(set_bdi_congested); * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit * write congestion. If no backing_devs are congested then just wait for the * next write to be completed. + * + * NOTE: in the current implementation, hardly any backing_devs are ever + * marked as congested, and write-completion is rarely reported (see calls + * to clear_bdi_congested). So this should not be assumed to ever wake before + * the timeout. */ long congestion_wait(int sync, long timeout) { @@ -1054,6 +1059,10 @@ EXPORT_SYMBOL(congestion_wait); * The return value is 0 if the sleep is for the full timeout. Otherwise, * it is the number of jiffies that were still remaining when the function * returned. return_value == timeout implies the function did not sleep. + * + * NOTE: in the current implementation, hardly any backing_devs are ever + * marked as congested, and write-completion is rarely reported (see calls + * to clear_bdi_congested). So this should not be assumed to sleep at all. */ long wait_iff_congested(int sync, long timeout) { From patchwork Tue Sep 14 00:13:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12491099 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3957DC433EF for ; Tue, 14 Sep 2021 00:28:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C715E6113B for ; Tue, 14 Sep 2021 00:28:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org C715E6113B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 70715940009; Mon, 13 Sep 2021 20:28:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6B6E26B0071; Mon, 13 Sep 2021 20:28:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 57EED940009; Mon, 13 Sep 2021 20:28:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0197.hostedemail.com [216.40.44.197]) by kanga.kvack.org (Postfix) with ESMTP id 48A116B006C for ; Mon, 13 Sep 2021 20:28:15 -0400 (EDT) Received: from smtpin32.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 00CBD8249980 for ; Tue, 14 Sep 2021 00:28:15 +0000 (UTC) X-FDA: 78584292150.32.F2C4E85 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf15.hostedemail.com (Postfix) with ESMTP id 91233D00009D for ; Tue, 14 Sep 2021 00:28:14 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 99029200AA; Tue, 14 Sep 2021 00:28:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1631579293; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4+AH5az6YB5d1G93t+IcgOjK97PdYCD1vgzzwp0b1A4=; b=alftfvknnXvvyyrEoULvS1VHdHrp4QigC7kX101FPGauGb0bejYoklkrO5xA/KiBsu3F5A SehbTi4gi727U4337mkMGjkx8t+h0PPoa4oFRLhjpjFPzxAHo+l0n3Dqn/89iwGDbf34eM qoiS23uj+YmmXgOCfedNGlHRM2IHNjA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1631579293; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4+AH5az6YB5d1G93t+IcgOjK97PdYCD1vgzzwp0b1A4=; b=7RVZAXOXvV0ntmE7QktWScNv2/X5V4egJV7QhcKOvnQ2UBuxavMTfKlMtx7vXisWIr81E2 iZnqbETZJnjKthCw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 12DC113ADE; Tue, 14 Sep 2021 00:28:06 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id xsn7MJbsP2EvawAAMHmgww (envelope-from ); Tue, 14 Sep 2021 00:28:06 +0000 From: NeilBrown To: Andrew Morton , Theodore Ts'o , Andreas Dilger , "Darrick J. Wong" , Matthew Wilcox , Mel Gorman Date: Tue, 14 Sep 2021 10:13:04 +1000 Subject: [PATCH 3/6] EXT4: Remove ENOMEM/congestion_wait() loops. 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: <163157838437.13293.14244628630141187199.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 Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=alftfvkn; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=7RVZAXOX; spf=pass (imf15.hostedemail.com: domain of neilb@suse.de designates 195.135.220.29 as permitted sender) smtp.mailfrom=neilb@suse.de; dmarc=pass (policy=none) header.from=suse.de X-Stat-Signature: rwzcq9xmwjrx8833p98odnffjk9gd6y5 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 91233D00009D X-HE-Tag: 1631579294-903758 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: Indefinite loops waiting for memory allocation are discouraged by documentation in gfp.h which says the use of __GFP_NOFAIL that it is definitely preferable to use the flag rather than opencode endless loop around allocator. Such loops that use congestion_wait() are particularly unwise as congestion_wait() is indistinguishable from schedule_timeout_uninterruptible() in practice - and should be deprecated. So this patch changes the two loops in ext4_ext_truncate() to use __GFP_NOFAIL instead of looping. As the allocation is multiple layers deeper in the call stack, this requires passing the EXT4_EX_NOFAIL flag down and handling it in various places. Of particular interest is the ext4_journal_start family of calls which can now have EXT4_EX_NOFAIL 'or'ed in to the 'type'. This could be seen as a blurring of types. However 'type' is 8 bits, and EXT4_EX_NOFAIL is a high bit, so it is safe in practice. jbd2__journal_start() is enhanced so that the gfp_t flags passed are used for *all* allocations. Signed-off-by: NeilBrown --- fs/ext4/ext4.h | 2 +- fs/ext4/ext4_jbd2.c | 8 +++++++- fs/ext4/extents.c | 49 +++++++++++++++++----------------------------- fs/ext4/extents_status.c | 35 +++++++++++++++++++-------------- fs/ext4/extents_status.h | 2 +- fs/ext4/indirect.c | 2 +- fs/ext4/inode.c | 6 +++--- fs/ext4/ioctl.c | 4 ++-- fs/ext4/super.c | 2 +- fs/jbd2/transaction.c | 8 ++++---- 10 files changed, 58 insertions(+), 60 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 90ff5acaf11f..52a34f5dfda2 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -3720,7 +3720,7 @@ extern int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, struct ext4_map_blocks *map, int flags); extern int ext4_ext_truncate(handle_t *, struct inode *); extern int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start, - ext4_lblk_t end); + ext4_lblk_t end, int nofail); extern void ext4_ext_init(struct super_block *); extern void ext4_ext_release(struct super_block *); extern long ext4_fallocate(struct file *file, int mode, loff_t offset, diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c index 6def7339056d..2bdda3b7a3e6 100644 --- a/fs/ext4/ext4_jbd2.c +++ b/fs/ext4/ext4_jbd2.c @@ -92,6 +92,12 @@ handle_t *__ext4_journal_start_sb(struct super_block *sb, unsigned int line, { journal_t *journal; int err; + gfp_t gfp_mask = GFP_NOFS; + + if (type & EXT4_EX_NOFAIL) { + gfp_mask |= __GFP_NOFAIL; + type &= ~EXT4_EX_NOFAIL; + } trace_ext4_journal_start(sb, blocks, rsv_blocks, revoke_creds, _RET_IP_); @@ -103,7 +109,7 @@ handle_t *__ext4_journal_start_sb(struct super_block *sb, unsigned int line, if (!journal || (EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY)) return ext4_get_nojournal(); return jbd2__journal_start(journal, blocks, rsv_blocks, revoke_creds, - GFP_NOFS, type, line); + gfp_mask, type, line); } int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index c0de30f25185..b7bc12aedf78 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -1488,7 +1488,7 @@ static int ext4_ext_search_left(struct inode *inode, static int ext4_ext_search_right(struct inode *inode, struct ext4_ext_path *path, ext4_lblk_t *logical, ext4_fsblk_t *phys, - struct ext4_extent *ret_ex) + struct ext4_extent *ret_ex, int nofail) { struct buffer_head *bh = NULL; struct ext4_extent_header *eh; @@ -1565,7 +1565,7 @@ static int ext4_ext_search_right(struct inode *inode, while (++depth < path->p_depth) { /* subtract from p_depth to get proper eh_depth */ bh = read_extent_tree_block(inode, block, - path->p_depth - depth, 0); + path->p_depth - depth, nofail); if (IS_ERR(bh)) return PTR_ERR(bh); eh = ext_block_hdr(bh); @@ -1574,7 +1574,7 @@ static int ext4_ext_search_right(struct inode *inode, put_bh(bh); } - bh = read_extent_tree_block(inode, block, path->p_depth - depth, 0); + bh = read_extent_tree_block(inode, block, path->p_depth - depth, nofail); if (IS_ERR(bh)) return PTR_ERR(bh); eh = ext_block_hdr(bh); @@ -2773,7 +2773,7 @@ ext4_ext_more_to_rm(struct ext4_ext_path *path) } int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start, - ext4_lblk_t end) + ext4_lblk_t end, int nofail) { struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); int depth = ext_depth(inode); @@ -2789,7 +2789,8 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start, ext_debug(inode, "truncate since %u to %u\n", start, end); /* probably first extent we're gonna free will be last in block */ - handle = ext4_journal_start_with_revoke(inode, EXT4_HT_TRUNCATE, + handle = ext4_journal_start_with_revoke(inode, + EXT4_HT_TRUNCATE | nofail, depth + 1, ext4_free_metadata_revoke_credits(inode->i_sb, depth)); if (IS_ERR(handle)) @@ -2877,7 +2878,7 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start, */ lblk = ex_end + 1; err = ext4_ext_search_right(inode, path, &lblk, &pblk, - NULL); + NULL, nofail); if (err < 0) goto out; if (pblk) { @@ -2899,10 +2900,6 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start, } else { path = kcalloc(depth + 1, sizeof(struct ext4_ext_path), GFP_NOFS | __GFP_NOFAIL); - if (path == NULL) { - ext4_journal_stop(handle); - return -ENOMEM; - } path[0].p_maxdepth = path[0].p_depth = depth; path[0].p_hdr = ext_inode_hdr(inode); i = 0; @@ -2955,7 +2952,7 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start, memset(path + i + 1, 0, sizeof(*path)); bh = read_extent_tree_block(inode, ext4_idx_pblock(path[i].p_idx), depth - i - 1, - EXT4_EX_NOCACHE); + EXT4_EX_NOCACHE | nofail); if (IS_ERR(bh)) { /* should we reset i_size? */ err = PTR_ERR(bh); @@ -4186,7 +4183,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, if (err) goto out; ar.lright = map->m_lblk; - err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright, &ex2); + err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright, &ex2, 0); if (err < 0) goto out; @@ -4368,23 +4365,13 @@ int ext4_ext_truncate(handle_t *handle, struct inode *inode) last_block = (inode->i_size + sb->s_blocksize - 1) >> EXT4_BLOCK_SIZE_BITS(sb); -retry: err = ext4_es_remove_extent(inode, last_block, - EXT_MAX_BLOCKS - last_block); - if (err == -ENOMEM) { - cond_resched(); - congestion_wait(BLK_RW_ASYNC, HZ/50); - goto retry; - } + EXT_MAX_BLOCKS - last_block, + EXT4_EX_NOFAIL); if (err) return err; -retry_remove_space: - err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1); - if (err == -ENOMEM) { - cond_resched(); - congestion_wait(BLK_RW_ASYNC, HZ/50); - goto retry_remove_space; - } + err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1, + EXT4_EX_NOFAIL); return err; } @@ -5322,13 +5309,13 @@ static int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len) ext4_discard_preallocations(inode, 0); ret = ext4_es_remove_extent(inode, punch_start, - EXT_MAX_BLOCKS - punch_start); + EXT_MAX_BLOCKS - punch_start, 0); if (ret) { up_write(&EXT4_I(inode)->i_data_sem); goto out_stop; } - ret = ext4_ext_remove_space(inode, punch_start, punch_stop - 1); + ret = ext4_ext_remove_space(inode, punch_start, punch_stop - 1, 0); if (ret) { up_write(&EXT4_I(inode)->i_data_sem); goto out_stop; @@ -5510,7 +5497,7 @@ static int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len) } ret = ext4_es_remove_extent(inode, offset_lblk, - EXT_MAX_BLOCKS - offset_lblk); + EXT_MAX_BLOCKS - offset_lblk, 0); if (ret) { up_write(&EXT4_I(inode)->i_data_sem); goto out_stop; @@ -5574,10 +5561,10 @@ ext4_swap_extents(handle_t *handle, struct inode *inode1, BUG_ON(!inode_is_locked(inode1)); BUG_ON(!inode_is_locked(inode2)); - *erp = ext4_es_remove_extent(inode1, lblk1, count); + *erp = ext4_es_remove_extent(inode1, lblk1, count, 0); if (unlikely(*erp)) return 0; - *erp = ext4_es_remove_extent(inode2, lblk2, count); + *erp = ext4_es_remove_extent(inode2, lblk2, count, 0); if (unlikely(*erp)) return 0; diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c index 9a3a8996aacf..7f7711a2ea44 100644 --- a/fs/ext4/extents_status.c +++ b/fs/ext4/extents_status.c @@ -144,9 +144,10 @@ static struct kmem_cache *ext4_es_cachep; static struct kmem_cache *ext4_pending_cachep; -static int __es_insert_extent(struct inode *inode, struct extent_status *newes); +static int __es_insert_extent(struct inode *inode, struct extent_status *newes, + int nofail); static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk, - ext4_lblk_t end, int *reserved); + ext4_lblk_t end, int *reserved, int nofail); static int es_reclaim_extents(struct ext4_inode_info *ei, int *nr_to_scan); static int __es_shrink(struct ext4_sb_info *sbi, int nr_to_scan, struct ext4_inode_info *locked_ei); @@ -452,10 +453,11 @@ static void ext4_es_list_del(struct inode *inode) static struct extent_status * ext4_es_alloc_extent(struct inode *inode, ext4_lblk_t lblk, ext4_lblk_t len, - ext4_fsblk_t pblk) + ext4_fsblk_t pblk, int nofail) { struct extent_status *es; - es = kmem_cache_alloc(ext4_es_cachep, GFP_ATOMIC); + es = kmem_cache_alloc(ext4_es_cachep, + GFP_ATOMIC | (nofail ? __GFP_NOFAIL : 0)); if (es == NULL) return NULL; es->es_lblk = lblk; @@ -754,7 +756,8 @@ static inline void ext4_es_insert_extent_check(struct inode *inode, } #endif -static int __es_insert_extent(struct inode *inode, struct extent_status *newes) +static int __es_insert_extent(struct inode *inode, struct extent_status *newes, + int nofail) { struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree; struct rb_node **p = &tree->root.rb_node; @@ -795,7 +798,7 @@ static int __es_insert_extent(struct inode *inode, struct extent_status *newes) } es = ext4_es_alloc_extent(inode, newes->es_lblk, newes->es_len, - newes->es_pblk); + newes->es_pblk, nofail); if (!es) return -ENOMEM; rb_link_node(&es->rb_node, parent, p); @@ -848,11 +851,11 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk, ext4_es_insert_extent_check(inode, &newes); write_lock(&EXT4_I(inode)->i_es_lock); - err = __es_remove_extent(inode, lblk, end, NULL); + err = __es_remove_extent(inode, lblk, end, NULL, 0); if (err != 0) goto error; retry: - err = __es_insert_extent(inode, &newes); + err = __es_insert_extent(inode, &newes, 0); if (err == -ENOMEM && __es_shrink(EXT4_SB(inode->i_sb), 128, EXT4_I(inode))) goto retry; @@ -902,7 +905,7 @@ void ext4_es_cache_extent(struct inode *inode, ext4_lblk_t lblk, es = __es_tree_search(&EXT4_I(inode)->i_es_tree.root, lblk); if (!es || es->es_lblk > end) - __es_insert_extent(inode, &newes); + __es_insert_extent(inode, &newes, 0); write_unlock(&EXT4_I(inode)->i_es_lock); } @@ -1294,6 +1297,7 @@ static unsigned int get_rsvd(struct inode *inode, ext4_lblk_t end, * @lblk - first block in range * @end - last block in range * @reserved - number of cluster reservations released + * @nofail - EXT4_EX_NOFAIL if __GFP_NOFAIL should be used * * If @reserved is not NULL and delayed allocation is enabled, counts * block/cluster reservations freed by removing range and if bigalloc @@ -1301,7 +1305,7 @@ static unsigned int get_rsvd(struct inode *inode, ext4_lblk_t end, * error code on failure. */ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk, - ext4_lblk_t end, int *reserved) + ext4_lblk_t end, int *reserved, int nofail) { struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree; struct rb_node *node; @@ -1350,7 +1354,7 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk, orig_es.es_len - len2; ext4_es_store_pblock_status(&newes, block, ext4_es_status(&orig_es)); - err = __es_insert_extent(inode, &newes); + err = __es_insert_extent(inode, &newes, nofail); if (err) { es->es_lblk = orig_es.es_lblk; es->es_len = orig_es.es_len; @@ -1426,12 +1430,13 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk, * @inode - file containing range * @lblk - first block in range * @len - number of blocks to remove + * @nofail - EXT4_EX_NOFAIL if __GFP_NOFAIL should be used * * Reduces block/cluster reservation count and for bigalloc cancels pending * reservations as needed. Returns 0 on success, error code on failure. */ int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk, - ext4_lblk_t len) + ext4_lblk_t len, int nofail) { ext4_lblk_t end; int err = 0; @@ -1456,7 +1461,7 @@ int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk, * is reclaimed. */ write_lock(&EXT4_I(inode)->i_es_lock); - err = __es_remove_extent(inode, lblk, end, &reserved); + err = __es_remove_extent(inode, lblk, end, &reserved, nofail); write_unlock(&EXT4_I(inode)->i_es_lock); ext4_es_print_tree(inode); ext4_da_release_space(inode, reserved); @@ -2003,11 +2008,11 @@ int ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk, write_lock(&EXT4_I(inode)->i_es_lock); - err = __es_remove_extent(inode, lblk, lblk, NULL); + err = __es_remove_extent(inode, lblk, lblk, NULL, 0); if (err != 0) goto error; retry: - err = __es_insert_extent(inode, &newes); + err = __es_insert_extent(inode, &newes, 0); if (err == -ENOMEM && __es_shrink(EXT4_SB(inode->i_sb), 128, EXT4_I(inode))) goto retry; diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h index 4ec30a798260..23d77094a165 100644 --- a/fs/ext4/extents_status.h +++ b/fs/ext4/extents_status.h @@ -134,7 +134,7 @@ extern void ext4_es_cache_extent(struct inode *inode, ext4_lblk_t lblk, ext4_lblk_t len, ext4_fsblk_t pblk, unsigned int status); extern int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk, - ext4_lblk_t len); + ext4_lblk_t len, int nofail); extern void ext4_es_find_extent_range(struct inode *inode, int (*match_fn)(struct extent_status *es), ext4_lblk_t lblk, ext4_lblk_t end, diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c index 89efa78ed4b2..910e87aea7be 100644 --- a/fs/ext4/indirect.c +++ b/fs/ext4/indirect.c @@ -1125,7 +1125,7 @@ void ext4_ind_truncate(handle_t *handle, struct inode *inode) return; } - ext4_es_remove_extent(inode, last_block, EXT_MAX_BLOCKS - last_block); + ext4_es_remove_extent(inode, last_block, EXT_MAX_BLOCKS - last_block, 0); /* * The orphan list entry will now protect us from any crash which diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d18852d6029c..24246043d94b 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1575,7 +1575,7 @@ static void mpage_release_unused_pages(struct mpage_da_data *mpd, ext4_lblk_t start, last; start = index << (PAGE_SHIFT - inode->i_blkbits); last = end << (PAGE_SHIFT - inode->i_blkbits); - ext4_es_remove_extent(inode, start, last - start + 1); + ext4_es_remove_extent(inode, start, last - start + 1, 0); } pagevec_init(&pvec); @@ -4109,7 +4109,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length) ext4_discard_preallocations(inode, 0); ret = ext4_es_remove_extent(inode, first_block, - stop_block - first_block); + stop_block - first_block, 0); if (ret) { up_write(&EXT4_I(inode)->i_data_sem); goto out_stop; @@ -4117,7 +4117,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length) if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) ret = ext4_ext_remove_space(inode, first_block, - stop_block - 1); + stop_block - 1, 0); else ret = ext4_ind_remove_space(handle, inode, first_block, stop_block); diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index 606dee9e08a3..e4de05a6b976 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -79,8 +79,8 @@ static void swap_inode_data(struct inode *inode1, struct inode *inode2) (ei1->i_flags & ~EXT4_FL_SHOULD_SWAP); ei2->i_flags = tmp | (ei2->i_flags & ~EXT4_FL_SHOULD_SWAP); swap(ei1->i_disksize, ei2->i_disksize); - ext4_es_remove_extent(inode1, 0, EXT_MAX_BLOCKS); - ext4_es_remove_extent(inode2, 0, EXT_MAX_BLOCKS); + ext4_es_remove_extent(inode1, 0, EXT_MAX_BLOCKS, 0); + ext4_es_remove_extent(inode2, 0, EXT_MAX_BLOCKS, 0); isize = i_size_read(inode1); i_size_write(inode1, i_size_read(inode2)); diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 0775950ee84e..947e8376a35a 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1393,7 +1393,7 @@ void ext4_clear_inode(struct inode *inode) invalidate_inode_buffers(inode); clear_inode(inode); ext4_discard_preallocations(inode, 0); - ext4_es_remove_extent(inode, 0, EXT_MAX_BLOCKS); + ext4_es_remove_extent(inode, 0, EXT_MAX_BLOCKS, 0); dquot_drop(inode); if (EXT4_I(inode)->jinode) { jbd2_journal_release_jbd_inode(EXT4_JOURNAL(inode), diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index 6a3caedd2285..23e0f003d43b 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -476,9 +476,9 @@ static int start_this_handle(journal_t *journal, handle_t *handle, } /* Allocate a new handle. This should probably be in a slab... */ -static handle_t *new_handle(int nblocks) +static handle_t *new_handle(int nblocks, gfp_t gfp) { - handle_t *handle = jbd2_alloc_handle(GFP_NOFS); + handle_t *handle = jbd2_alloc_handle(gfp); if (!handle) return NULL; handle->h_total_credits = nblocks; @@ -505,13 +505,13 @@ handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks, nblocks += DIV_ROUND_UP(revoke_records, journal->j_revoke_records_per_block); - handle = new_handle(nblocks); + handle = new_handle(nblocks, gfp_mask); if (!handle) return ERR_PTR(-ENOMEM); if (rsv_blocks) { handle_t *rsv_handle; - rsv_handle = new_handle(rsv_blocks); + rsv_handle = new_handle(rsv_blocks, gfp_mask); if (!rsv_handle) { jbd2_free_handle(handle); return ERR_PTR(-ENOMEM); From patchwork Tue Sep 14 00:13:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12491101 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 089D9C4332F for ; Tue, 14 Sep 2021 00:28:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AFED761130 for ; Tue, 14 Sep 2021 00:28:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AFED761130 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 5A7EC94000A; Mon, 13 Sep 2021 20:28:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 556C06B0071; Mon, 13 Sep 2021 20:28:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4463494000A; Mon, 13 Sep 2021 20:28:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0121.hostedemail.com [216.40.44.121]) by kanga.kvack.org (Postfix) with ESMTP id 38D0A6B006C for ; Mon, 13 Sep 2021 20:28:23 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id D807A8249980 for ; Tue, 14 Sep 2021 00:28:22 +0000 (UTC) X-FDA: 78584292444.26.E54D5E5 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf29.hostedemail.com (Postfix) with ESMTP id 7F3F5900024A for ; Tue, 14 Sep 2021 00:28:22 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 8E60D200AA; Tue, 14 Sep 2021 00:28:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1631579301; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=K2Rgi41wxZueRRJfJ3e7t139IMXGOwOFm/IW/86sxa8=; b=lyzjdxtY3SnzCwzK/kuZJUC9SY4Xs7ZXRw+PP/oAiwssdGGvZuytAC5YDSWdV3wkeEbVUN eyns/Vbu/tlvelFBIDmgZ5FHtcnjomj2R4y823Hws1tCEgwJKhsPS/c5wzVgfdDw/cMM2W VDrSFwyOEF2ta5PPGMVNOKXvEhEr0jw= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1631579301; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=K2Rgi41wxZueRRJfJ3e7t139IMXGOwOFm/IW/86sxa8=; b=QEL/DIW6vsNM7xl0L40jcqiiJLi/KiVfzJJKmTMtPziFOdCdB0wIt8hA78gAu/sb81FJoL 0TOAkRCT3w8YOPDQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 29D6613ADE; Tue, 14 Sep 2021 00:28:17 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id KmZZNqHsP2FCawAAMHmgww (envelope-from ); Tue, 14 Sep 2021 00:28:17 +0000 From: NeilBrown To: Andrew Morton , Theodore Ts'o , Andreas Dilger , "Darrick J. Wong" , Matthew Wilcox , Mel Gorman Date: Tue, 14 Sep 2021 10:13:04 +1000 Subject: [PATCH 4/6] EXT4: remove congestion_wait from ext4_bio_write_page, and simplify 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: <163157838439.13293.3505783933403734827.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: rspam04 X-Rspamd-Queue-Id: 7F3F5900024A X-Stat-Signature: s6zd56ndr5f1sctxiue3xykfq4yuju14 Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=lyzjdxtY; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b="QEL/DIW6"; spf=pass (imf29.hostedemail.com: domain of neilb@suse.de designates 195.135.220.29 as permitted sender) smtp.mailfrom=neilb@suse.de; dmarc=pass (policy=none) header.from=suse.de X-HE-Tag: 1631579302-31980 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: congestion_wait() is indistinguishable from schedule_timeout_uninterruptible(). It is best avoided and should be deprecated. It is not needed in ext4_bio_write_page(). There are two cases. If there are no ->io_bio yet, then it is appropriate to use __GFP_NOFAIL which does the waiting in a better place. The code already uses this flag on the second attempt. This patch changes to it always use that flag for this case. If there *are* ->io_bio (in which case the allocation was non-blocking) we submit the io and return the first case. No waiting is needed in this case. So remove the congestion_wait() call, and simplify the code so that the two cases are somewhat clearer. Remove the "if (io->io_bio)" before calling ext4_io_submit() as that test is performed internally by that function. Signed-off-by: NeilBrown --- fs/ext4/page-io.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index f038d578d8d8..3b6ece0d3ad6 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -506,7 +506,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io, * can't happen in the common case of blocksize == PAGE_SIZE. */ if (fscrypt_inode_uses_fs_layer_crypto(inode) && nr_to_submit) { - gfp_t gfp_flags = GFP_NOFS; + gfp_t gfp_flags; unsigned int enc_bytes = round_up(len, i_blocksize(inode)); /* @@ -514,21 +514,18 @@ int ext4_bio_write_page(struct ext4_io_submit *io, * a waiting mask (i.e. request guaranteed allocation) on the * first page of the bio. Otherwise it can deadlock. */ + retry_encrypt: if (io->io_bio) gfp_flags = GFP_NOWAIT | __GFP_NOWARN; - retry_encrypt: + else + gfp_flags = GFP_NOFS | __GFP_NOFAIL; bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes, 0, gfp_flags); if (IS_ERR(bounce_page)) { ret = PTR_ERR(bounce_page); if (ret == -ENOMEM && (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) { - gfp_flags = GFP_NOFS; - if (io->io_bio) - ext4_io_submit(io); - else - gfp_flags |= __GFP_NOFAIL; - congestion_wait(BLK_RW_ASYNC, HZ/50); + ext4_io_submit(io); goto retry_encrypt; } From patchwork Tue Sep 14 00:13:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12491103 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DCE5C433EF for ; Tue, 14 Sep 2021 00:28:32 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 066FC61130 for ; Tue, 14 Sep 2021 00:28:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 066FC61130 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id A63226B006C; Mon, 13 Sep 2021 20:28:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A122894000C; Mon, 13 Sep 2021 20:28:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8D98E94000B; Mon, 13 Sep 2021 20:28:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0249.hostedemail.com [216.40.44.249]) by kanga.kvack.org (Postfix) with ESMTP id 81BFC6B006C for ; Mon, 13 Sep 2021 20:28:31 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 43A58181AEF30 for ; Tue, 14 Sep 2021 00:28:31 +0000 (UTC) X-FDA: 78584292822.20.3D2C2D8 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf24.hostedemail.com (Postfix) with ESMTP id E2E17B00009D for ; Tue, 14 Sep 2021 00:28:30 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id EB9EB200AC; Tue, 14 Sep 2021 00:28:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1631579309; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/fJh0QfLu557SRIcbnLQw5jXDd2d5nR20JToY2iryFI=; b=HxscG/LDiGhsXGcbasBy/GQpdvuvcezFHx0oNgiHTzBfG6jLNj7at1rWx8uH73RB9dCBEK 43zz46aMTEEwRh8Kab1HMrXpHEHa8osZ6ZQ61ivRCI80gCkcehQ/wgKC04GE2CRXQEzw46 /6h+o/IWXCBi0R7pu+/Q8WQGi/3R1gU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1631579309; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/fJh0QfLu557SRIcbnLQw5jXDd2d5nR20JToY2iryFI=; b=zy9E9ltAIbtS5E4r1Cp18Z6g2l7UU2NIsT6UJfPtYAJjWhnxeEspX3gl509vflmF/5AQeU SGQVgd8837Ms+xDQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 91DDF13ADE; Tue, 14 Sep 2021 00:28:26 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id EE9HFKrsP2FQawAAMHmgww (envelope-from ); Tue, 14 Sep 2021 00:28:26 +0000 From: NeilBrown To: Andrew Morton , Theodore Ts'o , Andreas Dilger , "Darrick J. Wong" , Matthew Wilcox , Mel Gorman Date: Tue, 14 Sep 2021 10:13:04 +1000 Subject: [PATCH 5/6] XFS: remove congestion_wait() loop from kmem_alloc() 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: <163157838439.13293.5032214643474179966.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: rspam04 X-Rspamd-Queue-Id: E2E17B00009D X-Stat-Signature: cmiqa7j91ytsip9taiwfy7dpz65qjgn5 Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b="HxscG/LD"; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=zy9E9ltA; spf=pass (imf24.hostedemail.com: domain of neilb@suse.de designates 195.135.220.29 as permitted sender) smtp.mailfrom=neilb@suse.de; dmarc=pass (policy=none) header.from=suse.de X-HE-Tag: 1631579310-537447 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. So remove the loop, instead specifying __GFP_NOFAIL if KM_MAYFAIL was not given. Signed-off-by: NeilBrown --- fs/xfs/kmem.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c index 6f49bf39183c..f545f3633f88 100644 --- a/fs/xfs/kmem.c +++ b/fs/xfs/kmem.c @@ -13,19 +13,11 @@ kmem_alloc(size_t size, xfs_km_flags_t flags) { int retries = 0; gfp_t lflags = kmem_flags_convert(flags); - void *ptr; trace_kmem_alloc(size, flags, _RET_IP_); - do { - ptr = kmalloc(size, lflags); - if (ptr || (flags & KM_MAYFAIL)) - return ptr; - if (!(++retries % 100)) - xfs_err(NULL, - "%s(%u) possible memory allocation deadlock size %u in %s (mode:0x%x)", - current->comm, current->pid, - (unsigned int)size, __func__, lflags); - congestion_wait(BLK_RW_ASYNC, HZ/50); - } while (1); + if (!(flags & KM_MAYFAIL)) + lflags |= __GFP_NOFAIL; + + return kmalloc(size, lflags); } From patchwork Tue Sep 14 00:13:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12491105 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0C89C433F5 for ; Tue, 14 Sep 2021 00:28:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5E98A60F4C for ; Tue, 14 Sep 2021 00:28:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5E98A60F4C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 04FD06B0071; Mon, 13 Sep 2021 20:28:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EF42594000C; Mon, 13 Sep 2021 20:28:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D94A794000B; Mon, 13 Sep 2021 20:28:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0236.hostedemail.com [216.40.44.236]) by kanga.kvack.org (Postfix) with ESMTP id C79076B0071 for ; Mon, 13 Sep 2021 20:28:42 -0400 (EDT) Received: from smtpin38.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 83E3318092E05 for ; Tue, 14 Sep 2021 00:28:42 +0000 (UTC) X-FDA: 78584293284.38.06650BF Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf15.hostedemail.com (Postfix) with ESMTP id 313B0D00009D for ; Tue, 14 Sep 2021 00:28:42 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 230D921E66; Tue, 14 Sep 2021 00:28:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1631579321; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kKg7RlKucOqg4kFvULlcfcgLDUa14h212dG0lQnULcE=; b=awMekhqm0ZNbe0UAJauJmcBwIc7nmh/WiO0Wm1svGCnQLjolPKb5AEyzgL6E7o+LIz4y5b lmX317K+JkPpTEpTlv/8PeWzfPTcsJIfAIpsVotoHrncS7969LnN3tar3wZGiAWm97fph1 H5B/qIkNeKC7yoT4eFeE3/rSAVYmUos= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1631579321; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kKg7RlKucOqg4kFvULlcfcgLDUa14h212dG0lQnULcE=; b=2y/BbnOYFFsEbgxZG3DjeobRaJHXJPGcoflnoSvt9f/Hntganr1MCbrR5BikDTWxDcsICr wEc7foc1STYeTIBA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 86E1A13ADE; Tue, 14 Sep 2021 00:28:36 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id kqaiEbTsP2FYawAAMHmgww (envelope-from ); Tue, 14 Sep 2021 00:28:36 +0000 From: NeilBrown To: Andrew Morton , Theodore Ts'o , Andreas Dilger , "Darrick J. 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; }