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 X-Spam-Level: X-Spam-Status: No, score=-15.7 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,URIBL_BLOCKED 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 61594C56202 for ; Thu, 26 Nov 2020 13:40:39 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D1F882223F for ; Thu, 26 Nov 2020 13:40:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="ajTwHAYd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D1F882223F Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 238246B0070; Thu, 26 Nov 2020 08:40:38 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1E7176B0075; Thu, 26 Nov 2020 08:40:38 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 041DB6B007E; Thu, 26 Nov 2020 08:40:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0043.hostedemail.com [216.40.44.43]) by kanga.kvack.org (Postfix) with ESMTP id CECD36B0070 for ; Thu, 26 Nov 2020 08:40:37 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 9B20C180AD806 for ; Thu, 26 Nov 2020 13:40:37 +0000 (UTC) X-FDA: 77526679314.20.toy59_1e0bf8b2737f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id 78301180C07A3 for ; Thu, 26 Nov 2020 13:40:37 +0000 (UTC) X-HE-Tag: toy59_1e0bf8b2737f X-Filterd-Recvd-Size: 3957 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf39.hostedemail.com (Postfix) with ESMTP for ; Thu, 26 Nov 2020 13:40:36 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1606398035; 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=9tpQ2yN+EcMyN7hnntqz+RkMEw6hXQibeFRMrMM5L2s=; b=ajTwHAYd5J0mqReqBekTnBlsHHrNFEO2eq6u4Ld8L6JTiJiyCw/6cPwlyL+/8n48mCToMO 9Fj6YnH2i8ERYfahSgxPKMouUumvsl2wEMjOv8qwNncauWTW6QbzM4Kca7A+6xWQxltQbk ddaiT31gMg3MoDiILTaN+MtEExvEZgY= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id A1D05AC6A; Thu, 26 Nov 2020 13:40:35 +0000 (UTC) Date: Thu, 26 Nov 2020 14:40:34 +0100 From: Michal Hocko To: Rik van Riel Cc: hughd@google.com, xuyu@linux.alibaba.com, akpm@linux-foundation.org, mgorman@suse.de, aarcange@redhat.com, willy@infradead.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, linux-mm@kvack.org, vbabka@suse.cz Subject: Re: [PATCH 2/3] mm,thp,shm: limit gfp mask to no more than specified Message-ID: <20201126134034.GI31550@dhcp22.suse.cz> References: <20201124194925.623931-1-riel@surriel.com> <20201124194925.623931-3-riel@surriel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201124194925.623931-3-riel@surriel.com> 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 24-11-20 14:49:24, Rik van Riel wrote: > Matthew Wilcox pointed out that the i915 driver opportunistically > allocates tmpfs memory, but will happily reclaim some of its > pool if no memory is available. > > Make sure the gfp mask used to opportunistically allocate a THP > is always at least as restrictive as the original gfp mask. I have brought this up in the previous version review and I feel my feedback hasn't been addressed. Please describe the expected behavior by those shmem users including GFP_KERNEL restriction which would make the THP flags incompatible. Is this a problem? Is there any actual problem if the THP uses its own set of flags? I am also not happy how those two sets of flags are completely detached and we can only expect surprises there. > Signed-off-by: Rik van Riel > Suggested-by: Matthew Wilcox > --- > mm/shmem.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 6c3cb192a88d..ee3cea10c2a4 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1531,6 +1531,26 @@ static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, > return page; > } > > +/* > + * Make sure huge_gfp is always more limited than limit_gfp. > + * Some of the flags set permissions, while others set limitations. > + */ > +static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp) > +{ > + gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM; > + gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY; > + gfp_t result = huge_gfp & ~allowflags; > + > + /* > + * Minimize the result gfp by taking the union with the deny flags, > + * and the intersection of the allow flags. > + */ > + result |= (limit_gfp & denyflags); > + result |= (huge_gfp & limit_gfp) & allowflags; > + > + return result; > +} > + > static struct page *shmem_alloc_hugepage(gfp_t gfp, > struct shmem_inode_info *info, pgoff_t index) > { > @@ -1889,6 +1909,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, > > alloc_huge: > huge_gfp = vma_thp_gfp_mask(vma); > + huge_gfp = limit_gfp_mask(huge_gfp, gfp); > page = shmem_alloc_and_acct_page(huge_gfp, inode, index, true); > if (IS_ERR(page)) { > alloc_nohuge: > -- > 2.25.4 > -- Michal Hocko SUSE Labs