From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f182.google.com (mail-wi0-f182.google.com [209.85.212.182]) by kanga.kvack.org (Postfix) with ESMTP id EAEC46B006E for ; Mon, 2 Mar 2015 08:55:41 -0500 (EST) Received: by wivr20 with SMTP id r20so14982764wiv.2 for ; Mon, 02 Mar 2015 05:55:41 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id m8si22587147wjw.48.2015.03.02.05.55.35 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 02 Mar 2015 05:55:35 -0800 (PST) From: Michal Hocko Subject: [RFC 2/4] jbd2: revert must-not-fail allocation loops back to GFP_NOFAIL Date: Mon, 2 Mar 2015 14:54:41 +0100 Message-Id: <1425304483-7987-3-git-send-email-mhocko@suse.cz> In-Reply-To: <1425304483-7987-1-git-send-email-mhocko@suse.cz> References: <1425304483-7987-1-git-send-email-mhocko@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Andrew Morton , Johannes Weiner , David Rientjes , Dave Chinner , Theodore Ts'o , Mel Gorman , Tetsuo Handa , "David S. Miller" , sparclinux@vger.kernel.org, Vipul Pandya , netdev@vger.kernel.org, LKML This basically reverts 47def82672b3 (jbd2: Remove __GFP_NOFAIL from jbd2 layer). The deprecation of __GFP_NOFAIL was a bad choice because it led to open coding the endless loop around the allocator rather than removing the dependency on the non failing allocation. So the deprecation was a clear failure and the reality tells us that __GFP_NOFAIL is not even close to go away. It is still true that __GFP_NOFAIL allocations are generally discouraged and new uses should be evaluated and an alternative (pre-allocations or reservations) should be considered but it doesn't make any sense to lie the allocator about the requirements. Allocator can take steps to help making a progress if it knows the requirements. Signed-off-by: Michal Hocko --- fs/jbd2/journal.c | 11 +---------- fs/jbd2/transaction.c | 20 +++++++------------- 2 files changed, 8 insertions(+), 23 deletions(-) diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index b96bd8076b70..0bc333b4a594 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -371,16 +371,7 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction, */ J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in)); -retry_alloc: - new_bh = alloc_buffer_head(GFP_NOFS); - if (!new_bh) { - /* - * Failure is not an option, but __GFP_NOFAIL is going - * away; so we retry ourselves here. - */ - congestion_wait(BLK_RW_ASYNC, HZ/50); - goto retry_alloc; - } + new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL); /* keep subsequent assertions sane */ atomic_set(&new_bh->b_count, 1); diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index 5f09370c90a8..dac4523fa142 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -278,22 +278,16 @@ static int start_this_handle(journal_t *journal, handle_t *handle, alloc_transaction: if (!journal->j_running_transaction) { + /* + * If __GFP_FS is not present, then we may be being called from + * inside the fs writeback layer, so we MUST NOT fail. + */ + if ((gfp_mask & __GFP_FS) == 0) + gfp_mask |= __GFP_NOFAIL; new_transaction = kmem_cache_zalloc(transaction_cache, gfp_mask); - if (!new_transaction) { - /* - * If __GFP_FS is not present, then we may be - * being called from inside the fs writeback - * layer, so we MUST NOT fail. Since - * __GFP_NOFAIL is going away, we will arrange - * to retry the allocation ourselves. - */ - if ((gfp_mask & __GFP_FS) == 0) { - congestion_wait(BLK_RW_ASYNC, HZ/50); - goto alloc_transaction; - } + if (!new_transaction) return -ENOMEM; - } } jbd_debug(3, "New handle %p going live.\n", handle); -- 2.1.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org