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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4FDAC77B7A for ; Sat, 20 May 2023 22:44:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9C1E8900004; Sat, 20 May 2023 18:44:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 971A4900003; Sat, 20 May 2023 18:44:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 83979900004; Sat, 20 May 2023 18:44:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 719E4900003 for ; Sat, 20 May 2023 18:44:51 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 3EBF5120BFE for ; Sat, 20 May 2023 22:44:51 +0000 (UTC) X-FDA: 80812114782.02.6C55C5B Received: from www262.sakura.ne.jp (www262.sakura.ne.jp [202.181.97.72]) by imf29.hostedemail.com (Postfix) with ESMTP id 1534212000E for ; Sat, 20 May 2023 22:44:47 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=none; dmarc=none; spf=none (imf29.hostedemail.com: domain of penguin-kernel@I-love.SAKURA.ne.jp has no SPF policy when checking 202.181.97.72) smtp.mailfrom=penguin-kernel@I-love.SAKURA.ne.jp ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1684622688; h=from:from:sender:reply-to:subject:subject: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=WbfzFnMrGuKehyMyFVGA+gKu6pKBYeFdxj6oxBEzsfI=; b=IHqRpFeky1MTl5VI0dw2cz2OpfG88Lmc3DMYkfGhzmNwbnGAdO+TpsIJYqVuYLiJFStkbn z8esMyIASVI8wsIEmJO5Su0SERjrANE8zii3FJvHkYSoklWTg2YHdq4mNhjuc7l4vPylKL 52e0R9h3UuUAIhL4Jt+X1CCiujYi6a0= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=none; dmarc=none; spf=none (imf29.hostedemail.com: domain of penguin-kernel@I-love.SAKURA.ne.jp has no SPF policy when checking 202.181.97.72) smtp.mailfrom=penguin-kernel@I-love.SAKURA.ne.jp ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1684622688; a=rsa-sha256; cv=none; b=u5CdwqHhVkr5tc0Gn/3it/mHPPDf8lgo3dj5NfcOmOMe7fXli5f+GbTVe3MCRc+lKka0/T eEm57BeUaigfnih33fZEbpMZQF1M5tln3LLqSKh2UcSgk0kUjqJj85ZOR3HGaFJ5TZSiKd d0OLieQ+HwuJ10pjJKZ/R0e6vM2Rmzk= Received: from fsav118.sakura.ne.jp (fsav118.sakura.ne.jp [27.133.134.245]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 34KMiMiH053860; Sun, 21 May 2023 07:44:22 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav118.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav118.sakura.ne.jp); Sun, 21 May 2023 07:44:22 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav118.sakura.ne.jp) Received: from [192.168.1.6] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 34KMiMMB053856 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Sun, 21 May 2023 07:44:22 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: <9c44eba9-5979-ee78-c9c8-626edc00f975@I-love.SAKURA.ne.jp> Date: Sun, 21 May 2023 07:44:20 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH] lib/stackdepot: stackdepot: don't use __GFP_KSWAPD_RECLAIM from __stack_depot_save() if atomic context Content-Language: en-US From: Tetsuo Handa To: syzbot , syzkaller-bugs@googlegroups.com, Mel Gorman , "Huang, Ying" , Vlastimil Babka , Andrew Morton , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Andrey Ryabinin Cc: kasan-dev , linux-mm References: <000000000000cef3a005fc1bcc80@google.com> <48a6a627-183d-6331-0d8d-ae4b1d4b0101@I-love.SAKURA.ne.jp> In-Reply-To: <48a6a627-183d-6331-0d8d-ae4b1d4b0101@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 1534212000E X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: ba89ufw8dhd7wknd3m1nkqegz4smbda3 X-HE-Tag: 1684622687-836298 X-HE-Meta: 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 BLtiGDec CAaEUYVk5quNOkYXZBkaKR+4u+0BxsKiECplschhcviHb/dPYXsPsjCyoEc1lBiP30592g/0Y7Tewzc8QtPYG/6QWaGO/PuwCSIO9ssPs3Lw+Pg2ZKPKCP5YmeMUTsNrQpKJ79O25N1J6iVbupLVxNCXe651jUxbZ8K4KHaZb5Vs46I8r+zOR4HlPnsm/YLqQ9WRCBQiMSLU76tQjVyIv5c1Ip5PgLNLY7UM7R5ow+DKhYmgKrAeS84QBd07vQ0BEb422DtvmaPGNSGjP2xj97CkI3WmPF4YlOyBP35Jiu/HGUKc+31N/Ss9cHzPE1IpOwJeh1Ybkgsr7S5YbLU+YRKPYFnOuDU6uXBgMta4sTGm2xChl2pTK5AFIGCpJJwpNM/WQ4fUVynQRm2Q87VyQ0LEHImxr1Df/lon2I28uLVziEFg= 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 2023/05/20 22:14, Tetsuo Handa wrote: > On 2023/05/20 20:33, Tetsuo Handa wrote: >> @@ -405,7 +405,10 @@ depot_stack_handle_t __stack_depot_save(unsigned long *entries, >> * contexts and I/O. >> */ >> alloc_flags &= ~GFP_ZONEMASK; >> - alloc_flags &= (GFP_ATOMIC | GFP_KERNEL); >> + if (!(alloc_flags & __GFP_DIRECT_RECLAIM)) >> + alloc_flags &= __GFP_HIGH; >> + else >> + alloc_flags &= GFP_KERNEL; >> alloc_flags |= __GFP_NOWARN; > > Well, comparing with a report which reached __stack_depot_save() via fill_pool() > ( https://syzkaller.appspot.com/bug?extid=358bb3e221c762a1adbb ), I feel that > above lines might be bogus. > > Maybe we want to enable __GFP_HIGH even if alloc_flags == GFP_NOWAIT because > fill_pool() uses __GFPHIGH | __GFP_NOWARN regardless of the caller's context. > Then, these lines could be simplified like below. > > if (!(alloc_flags & __GFP_DIRECT_RECLAIM)) > alloc_flags = __GFP_HIGH | __GFP_NOWARN; > else > alloc_flags = (alloc_flags & GFP_KERNEL) | __GFP_NOWARN; > > How is the importance of memory allocation in __stack_depot_save() ? > If allocation failure is welcome, maybe we should not trigger OOM killer > by clearing __GFP_NORETRY when alloc_flags contained __GFP_FS ... > >> page = alloc_pages(alloc_flags, DEPOT_POOL_ORDER); >> if (page) > Well, since stackdepot itself simply use GFP flags supplied by kasan, this should be considered as a kasan's problem? __kasan_record_aux_stack() { alloc_meta->aux_stack[0] = kasan_save_stack(GFP_NOWAIT, can_alloc); // May deadlock due to including __GFP_KSWAPD_RECLAIM bit. } Any atomic allocation used by KASAN needs to drop __GFP_KSWAPD_RECLAIM bit. Where do we want to drop this bit (in the caller side, or in the callee side)?