From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 87E49C433FE for ; Wed, 27 Oct 2021 06:46:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 27131610EA for ; Wed, 27 Oct 2021 06:46:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 27131610EA Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id B9648940008; Wed, 27 Oct 2021 02:46:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B467B940007; Wed, 27 Oct 2021 02:46:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A0E3B940008; Wed, 27 Oct 2021 02:46:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0240.hostedemail.com [216.40.44.240]) by kanga.kvack.org (Postfix) with ESMTP id 93DB5940007 for ; Wed, 27 Oct 2021 02:46:56 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 5079C39486 for ; Wed, 27 Oct 2021 06:46:56 +0000 (UTC) X-FDA: 78741284832.30.5ED75BF Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf12.hostedemail.com (Postfix) with ESMTP id B9AF010003CB for ; Wed, 27 Oct 2021 06:46:55 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 4D7181FD40; Wed, 27 Oct 2021 06:46:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1635317214; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JtEp7W6kqDz9//t9/FGapgwQuT5/r1usoFaQkwqby9E=; b=FDmdB9fYRwlKJ3E79hZPHBFM0sQgBl3h6/7c5z8Cn4UB0NHxo6rfMENmSijKMv/KzPvl45 JNKw0FGA6Eug03ZccP/Aq9kCEgEEp7J4AO5C8/f+UMaFgzl3SJKLaVmqIbqFxDmiMt5nXk QZEy3v0rwYGizwWHHWsRtvWkLHUiXIw= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 32DF5A3B85; Wed, 27 Oct 2021 06:46:54 +0000 (UTC) Date: Wed, 27 Oct 2021 08:46:50 +0200 From: Michal Hocko To: Uladzislau Rezki Cc: Linux Memory Management List , Dave Chinner , Neil Brown , Andrew Morton , Christoph Hellwig , linux-fsdevel@vger.kernel.org, LKML , Ilya Dryomov , Jeff Layton Subject: Re: [PATCH 2/4] mm/vmalloc: add support for __GFP_NOFAIL Message-ID: References: <20211025150223.13621-1-mhocko@kernel.org> <20211025150223.13621-3-mhocko@kernel.org> <20211026193315.GA1860@pc638.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211026193315.GA1860@pc638.lan> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B9AF010003CB X-Stat-Signature: 9jdh9x6gnfsdzu7aa4dazd6ae81qj8iu Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=FDmdB9fY; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf12.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com X-HE-Tag: 1635317215-943922 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 Tue 26-10-21 21:33:15, Uladzislau Rezki wrote: > On Tue, Oct 26, 2021 at 06:28:52PM +0200, Michal Hocko wrote: > > On Tue 26-10-21 17:48:32, Uladzislau Rezki wrote: > > > > From: Michal Hocko > > > > > > > > Dave Chinner has mentioned that some of the xfs code would benefit from > > > > kvmalloc support for __GFP_NOFAIL because they have allocations that > > > > cannot fail and they do not fit into a single page. > > > > > > > > The larg part of the vmalloc implementation already complies with the > > > > given gfp flags so there is no work for those to be done. The area > > > > and page table allocations are an exception to that. Implement a retry > > > > loop for those. > > > > > > > > Add a short sleep before retrying. 1 jiffy is a completely random > > > > timeout. Ideally the retry would wait for an explicit event - e.g. > > > > a change to the vmalloc space change if the failure was caused by > > > > the space fragmentation or depletion. But there are multiple different > > > > reasons to retry and this could become much more complex. Keep the retry > > > > simple for now and just sleep to prevent from hogging CPUs. > > > > > > > > Signed-off-by: Michal Hocko > > > > --- > > > > mm/vmalloc.c | 10 +++++++++- > > > > 1 file changed, 9 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > > > index c6cc77d2f366..602649919a9d 100644 > > > > --- a/mm/vmalloc.c > > > > +++ b/mm/vmalloc.c > > > > @@ -2941,8 +2941,12 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, > > > > else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0) > > > > flags = memalloc_noio_save(); > > > > > > > > - ret = vmap_pages_range(addr, addr + size, prot, area->pages, > > > > + do { > > > > + ret = vmap_pages_range(addr, addr + size, prot, area->pages, > > > > page_shift); > > > > + if (ret < 0) > > > > + schedule_timeout_uninterruptible(1); > > > > + } while ((gfp_mask & __GFP_NOFAIL) && (ret < 0)); > > > > > > > > > > 1. > > > After that change a below code: > > > > > > > > > if (ret < 0) { > > > warn_alloc(orig_gfp_mask, NULL, > > > "vmalloc error: size %lu, failed to map pages", > > > area->nr_pages * PAGE_SIZE); > > > goto fail; > > > } > > > > > > > > > does not make any sense anymore. > > > > Why? Allocations without __GFP_NOFAIL can still fail, no? > > > Right. I meant one thing but wrote slightly differently. In case of > vmap_pages_range() fails(if __GFP_NOFAIL is set) should we emit any > warning message? Because either we can recover on a future iteration > or it stuck there infinitely so a user does not understand what happened. > From the other hand this is how __GFP_NOFAIL works, hm.. Yes, the page allocator doesn't warn either and I would like to keep this in sync. > Another thing, i see that schedule_timeout_uninterruptible(1) is invoked > for all cases even when __GFP_NOFAIL is not set, in that scenario we do > not want to wait, instead we should return back to a caller asap. Or am > i missing something here? OK, I will change that. -- Michal Hocko SUSE Labs