From patchwork Fri Apr 18 09:38:22 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 14057110 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 845E61EE7BE; Fri, 18 Apr 2025 09:45:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744969539; cv=none; b=EP/saHjIRe7wnbTVE/ngOia9c12z5m5iDuXj0zUtt5lgA3NZKc3Py7mZwb7h+sOyINoOfxdNfUPwXlSc7rx1ve1UkShFS4Y2SEfooNpbD2PrA2Cmh1XK4RKulm9VvQoqzVAHHm43BkkKRMdjQGXgpFoBVcDOYOBXvdhSuwX8u7g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744969539; c=relaxed/simple; bh=9OP0rY0s+GQSK1skRZFWmADM/fZR4WYEsAi8q5xSNJQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=g9Y0++nm/DiCIK39+akDGuVPxGC4vPj5r0HDY4p0j3rKtipk/Wxth3l5E/v4lNoKD1LWTItrkjGAZxAzPH1ajXGzqK4kmdyLv8xRozdvztrssjd3WHmNzHMCcuK19Ol1f8ox8BO5okqa/du3TeaUiJTVxS0YWf0ZJHxuWjxl1vk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Zf8xw14Xqz4f3lff; Fri, 18 Apr 2025 17:45:08 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 712AF1A07BB; Fri, 18 Apr 2025 17:45:33 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgBHrGA6HwJozQ1aJw--.29179S5; Fri, 18 Apr 2025 17:45:33 +0800 (CST) From: Yu Kuai To: axboe@kernel.dk, kbusch@kernel.org Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com Subject: [PATCH 1/5] brd: fix oops if write concurrent with discard Date: Fri, 18 Apr 2025 17:38:22 +0800 Message-Id: <20250418093826.3149293-2-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20250418093826.3149293-1-yukuai1@huaweicloud.com> References: <20250418093826.3149293-1-yukuai1@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: gCh0CgBHrGA6HwJozQ1aJw--.29179S5 X-Coremail-Antispam: 1UD129KBjvJXoWxZFyrGFWUGw1kAF1fAr1rCrg_yoW5Ar4kpF 43ArZ3J390qa15twnrXrn0kr15Wwn2kay8Way3Ca1Fgrs7uwnFyF1rJFWIq343Kr17CrZ3 CrWDJay8Zr18uwUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBC14x267AKxVW5JVWrJwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jr4l82xGYIkIc2 x26xkF7I0E14v26r1I6r4UM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCY1x0262kKe7AKxVWUtVW8Zw CF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j 6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64 vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_ Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r4j6F4UMIIF0x vEx4A2jsIEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIevJa73UjIFyTuYvjfU5a0mUUUUU X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ From: Yu Kuai User can issue write and discard concurrently, causing following BUG_ON: cpu0: brd_submit_bio brd_do_bve copy_to_brd_setup brd_insert_page xa_lock __xa_insert xa_unlock cpu1 brd_submit_bio brd_do_discard xa_lock page = __xa_erase __free_page xa_unlock copy_to_brd brd_lookup_page page = xa_load BUG_ON(!page) Fix this problem by skipping the write, and user will get zero data later if the page is not here. Also fix following checkpatch warnings: WARNING: Deprecated use of 'kmap_atomic', prefer 'kmap_local_page' instead WARNING: Deprecated use of 'kunmap_atomic', prefer 'kunmap_local' instead Fixes: 9ead7efc6f3f ("brd: implement discard support") Signed-off-by: Yu Kuai --- drivers/block/brd.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 292f127cae0a..a6e4f005cb76 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -133,22 +133,22 @@ static void copy_to_brd(struct brd_device *brd, const void *src, copy = min_t(size_t, n, PAGE_SIZE - offset); page = brd_lookup_page(brd, sector); - BUG_ON(!page); - - dst = kmap_atomic(page); - memcpy(dst + offset, src, copy); - kunmap_atomic(dst); + if (page) { + dst = kmap_local_page(page); + memcpy(dst + offset, src, copy); + kunmap_local(dst); + } if (copy < n) { src += copy; sector += copy >> SECTOR_SHIFT; copy = n - copy; page = brd_lookup_page(brd, sector); - BUG_ON(!page); - - dst = kmap_atomic(page); - memcpy(dst, src, copy); - kunmap_atomic(dst); + if (page) { + dst = kmap_local_page(page); + memcpy(dst, src, copy); + kunmap_local(dst); + } } } @@ -166,9 +166,9 @@ static void copy_from_brd(void *dst, struct brd_device *brd, copy = min_t(size_t, n, PAGE_SIZE - offset); page = brd_lookup_page(brd, sector); if (page) { - src = kmap_atomic(page); + src = kmap_local_page(page); memcpy(dst, src + offset, copy); - kunmap_atomic(src); + kunmap_local(src); } else memset(dst, 0, copy); @@ -178,9 +178,9 @@ static void copy_from_brd(void *dst, struct brd_device *brd, copy = n - copy; page = brd_lookup_page(brd, sector); if (page) { - src = kmap_atomic(page); + src = kmap_local_page(page); memcpy(dst, src, copy); - kunmap_atomic(src); + kunmap_local(src); } else memset(dst, 0, copy); } @@ -208,7 +208,7 @@ static int brd_do_bvec(struct brd_device *brd, struct page *page, goto out; } - mem = kmap_atomic(page); + mem = kmap_local_page(page); if (!op_is_write(opf)) { copy_from_brd(mem + off, brd, sector, len); flush_dcache_page(page); @@ -216,7 +216,7 @@ static int brd_do_bvec(struct brd_device *brd, struct page *page, flush_dcache_page(page); copy_to_brd(brd, mem + off, sector, len); } - kunmap_atomic(mem); + kunmap_local(mem); out: return err;