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 2F3EAC433EF for ; Wed, 24 Nov 2021 20:06:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 940976B0075; Wed, 24 Nov 2021 15:06:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8EFCA6B0078; Wed, 24 Nov 2021 15:06:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7B8836B007B; Wed, 24 Nov 2021 15:06:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0039.hostedemail.com [216.40.44.39]) by kanga.kvack.org (Postfix) with ESMTP id 67F6C6B0075 for ; Wed, 24 Nov 2021 15:06:32 -0500 (EST) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 19265886DF for ; Wed, 24 Nov 2021 20:06:22 +0000 (UTC) X-FDA: 78844905804.22.5FB7E6A Received: from mail-lj1-f180.google.com (mail-lj1-f180.google.com [209.85.208.180]) by imf10.hostedemail.com (Postfix) with ESMTP id 306CD6001E42 for ; Wed, 24 Nov 2021 20:06:18 +0000 (UTC) Received: by mail-lj1-f180.google.com with SMTP id e11so7758138ljo.13 for ; Wed, 24 Nov 2021 12:06:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20210112.gappssmtp.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=8PJKWzcbQpRMg5m74p+6M5/kpC7urCmsmIsgiELsr/0=; b=2ZI5vegyIoG6acR+kes/uJROMaJ2aACSGz8fkks5dalVL6jEzk/bg1qADHSrxMw8Ak ZLDvpgwSebeBHFwRnyP15LK3wqXoX6+W36RzJBA88un2EVbETvqS3aUhwPZl271ycToQ NZ7x1Qx5L5Mbz9js5gkhQFof9aV1vjQOZ9v6Msim0ndNC0neZ+uGREpuzMTihwcVLVDP XPAX6Z+PEVfcWC+bdm2ilovuhVcXcRTwdpGyLqpfmELKe7eFk0HvlJPdLWQ/ZTH4T+AF G+VJMqLMFqxt94ukbvVZjntbjt/agckVjxLk5zSrtUBgtIZkK21l+aW+j5DnYXcjz6N2 IYig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=8PJKWzcbQpRMg5m74p+6M5/kpC7urCmsmIsgiELsr/0=; b=lpde8xTbvtQzun1tizZBrqhu9qvCZtz+EBMp2fycQTQ7zkuc+Khqa88uMi4NmFVybd /EkzmRqZsyQxXUQW9buabwx8G54PWvfss7A7kI6vV2HvyBTf4xxvGVyfPZblK2zLDKhK s5A364TCvPgHaruIkYTmKox/aayzk7vGD9Zz44wsntQHIAejfZ2ZxxhL6HkPpxeqfiVq uO1+PipLOy9RtqsEubTMCYvSl9XrlcfwivdpuBSaqOrSu0EOnKd1gUJ+L0aYbmGD05Q0 SXrFg3KOXSFe+xEVtfsRNhAJ7sNUxFsG6E2q2khBj/0+l+6EH7awyxHG8cJSZyedpneW u/NA== X-Gm-Message-State: AOAM531ekdu2u/of9lzs3NX5+V/GotxofU1mQvdl+TwOgR33fruqzAHu fl0m/3xq6/BHAsfcyI/gro+geQ== X-Google-Smtp-Source: ABdhPJwS1eI5DF4E4Jhqei1WkuHP8bIqOzemopEz+xA19/4wma3Htfmcv9QuvhYnueV5DivwW/o8tg== X-Received: by 2002:a2e:a27c:: with SMTP id k28mr19256756ljm.98.1637784379894; Wed, 24 Nov 2021 12:06:19 -0800 (PST) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id l18sm73720lfc.97.2021.11.24.12.06.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Nov 2021 12:06:19 -0800 (PST) Received: by box.localdomain (Postfix, from userid 1000) id 8C7E1103635; Wed, 24 Nov 2021 23:06:18 +0300 (+03) Date: Wed, 24 Nov 2021 23:06:18 +0300 From: "Kirill A. Shutemov" To: Gang Li Cc: Hugh Dickins , Andrew Morton , "Kirill A. Shutemov" , stable@vger.kernel.org, songmuchun@bytedance.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] shmem: fix a race between shmem_unused_huge_shrink and shmem_evict_inode Message-ID: <20211124200618.adaxuxuksrinkigv@box.shutemov.name> References: <20211124094317.69719-1-ligang.bdlg@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211124094317.69719-1-ligang.bdlg@bytedance.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 306CD6001E42 X-Stat-Signature: pqsfh3c3gsfetmx58maa8u9o5ncg7an3 Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=shutemov-name.20210112.gappssmtp.com header.s=20210112 header.b=2ZI5vegy; spf=none (imf10.hostedemail.com: domain of kirill@shutemov.name has no SPF policy when checking 209.85.208.180) smtp.mailfrom=kirill@shutemov.name; dmarc=none X-HE-Tag: 1637784378-569073 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 Wed, Nov 24, 2021 at 05:43:16PM +0800, Gang Li wrote: > +move_back: > + /* inodes that are on @list and will not be deleted must be moved back to > + * global list before iput for two reasons: > + * 1. iput in lock: iput call shmem_evict_inode, then cause deadlock. > + * 2. iput before lock: shmem_evict_inode may grab the inode on @list, > + * which will cause race. > + */ > + spin_lock(&sbinfo->shrinklist_lock); > + list_move(&info->shrinklist, &sbinfo->shrinklist); > + sbinfo->shrinklist_len++; > + spin_unlock(&sbinfo->shrinklist_lock); > +put: > iput(inode); > } > > - spin_lock(&sbinfo->shrinklist_lock); > - list_splice_tail(&list, &sbinfo->shrinklist); > - sbinfo->shrinklist_len -= removed; > - spin_unlock(&sbinfo->shrinklist_lock); > - > return split; > } Okay, I guess it works. Locking is not pretty, but well.. Acked-by: Kirill A. Shutemov -- Kirill A. Shutemov