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[129.78.56.229]) by smtp.gmail.com with ESMTPSA id x18sm988009pfp.57.2021.04.28.20.45.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Apr 2021 20:45:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=n6WkvByEe9jHaNKcirxDjwO3RlSDD2tbJyA9X2kwaTQ=; b=bfPcKpaJTct/b2KwfgS8IybVcnm9hhayC5Pnp6OLWSF5gkgA8MquRdYGp74PdaqoWY pfsoqKZe8B13t2VyFkBNxF3U0QO/CMO24ivr8ZUcv9Bk5ME9QqdCj9WW+azt44dzwHNh 9v6S6S5ZHG2zW3JRKkXdWdqBmNlJpUENkpsTrAXtGN4EBWbNFJRl9nWHCWPLrMOlB6V2 DvJgsIgdevB674C7FyBgMCc3X3aq9sX1jj0WMhFION1Yqluq13ci8RuQbZmUcjrj8HAz KcE37M6cH1+vGKzlD+AHonwhRWJIUx/1JLdrQQFaxU3m/wvKJTDWrYPboYv9jOHWvgpZ /2Hw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=n6WkvByEe9jHaNKcirxDjwO3RlSDD2tbJyA9X2kwaTQ=; b=MO1BMIlk+XNv4Dk/gtJUK//EfmEGF9JrY2SoajcuXwr5yJxSX7C8Yp5XXUZC0lvFec I0/9ZEOVeFKq5qeKLWT3N3c3goz7WmWF/LwzX67i84dyOYPx13m5KAPBuGQI4NzNFArN LZX5/yGaK9tw238ky2R6zlaDwcCtYXXY7UB0/RdmTDmMZbBHAKY+wiwjwIkJTaUiN3ey 9V6+XFKb/Eg2pl/2ev1ueXYc8SLhlkDsuCdC7vomZpmmb4RfHBT864Xs6ATS7OgEROFu dhJEBePDfUT6YnRB1BSVhR7TNOd9tuckI9I6MwVw/6R6gQKfdW+6PfbV1yjfHpPHyEzO 6YDQ== X-Gm-Message-State: AOAM533s1IB45T4TdjoKMXOblWYJfybmpM5U+s7I1sFpuKySFi2jvUaG RopxV4UwWSYjCIcHLMt1yew= X-Google-Smtp-Source: ABdhPJyYGwGA8oBreArmkmwClyXIRL01ti98rbAHl2WUaNM56XVWv7IdnC8nmsb/0qMNVtwyzpMjEw== X-Received: by 2002:a17:90a:9405:: with SMTP id r5mr7683239pjo.139.1619667932282; Wed, 28 Apr 2021 20:45:32 -0700 (PDT) From: Baptiste Lepers Cc: trivial@kernel.org, Baptiste Lepers , Alexander Viro , Andrew Morton , Miklos Szeredi , Tejun Heo , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] poll: Ignore benign race on pwd->triggered Date: Thu, 29 Apr 2021 13:44:11 +1000 Message-Id: <20210429034411.6379-1-baptiste.lepers@gmail.com> X-Mailer: git-send-email 2.17.1 To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Mark data races to pwd->triggered as benign using READ_ONCE and WRITE_ONCE. These accesses are expected to be racy per comment. This patch is part of a series of patches aiming at reducing the number of benign races reported by KCSAN in order to focus future debugging effort on harmful races. Reported-by: syzbot+9b3fb64bcc8c1d807595@syzkaller.appspotmail.com Fixes: 5f820f648c92a ("poll: allow f_op->poll to sleep") Signed-off-by: Baptiste Lepers --- fs/select.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/select.c b/fs/select.c index 945896d0ac9e..e71b4d1a2606 100644 --- a/fs/select.c +++ b/fs/select.c @@ -194,7 +194,7 @@ static int __pollwake(wait_queue_entry_t *wait, unsigne= d mode, int sync, void *k * and is paired with smp_store_mb() in poll_schedule_timeout. */ smp_wmb(); - pwq->triggered =3D 1; + WRITE_ONCE(pwq->triggered, 1); =20 /* * Perform the default wake up operation using a dummy @@ -239,7 +239,7 @@ static int poll_schedule_timeout(struct poll_wqueues *p= wq, int state, int rc =3D -EINTR; =20 set_current_state(state); - if (!pwq->triggered) + if (!READ_ONCE(pwq->triggered)) rc =3D schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS); __set_current_state(TASK_RUNNING); =20 --=20 2.17.1