From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from va-2-38.ptr.blmpb.com (va-2-38.ptr.blmpb.com [209.127.231.38]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 053AE1D63F0 for ; Tue, 23 Jun 2026 08:00:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.127.231.38 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782201607; cv=none; b=rHkud2eg7xLIHMFjjBld/cdUQBW1PjmInLOezYJsYQn60Nha+Pe52waf4ru1tAAbnUjpPrWS+gVjAenj97WGiqEb4Sf865WSPeO36ULw3tT+sdhHISh8NuhaS67VgXxpzh57urD7I5UsviRZPytXS+/F0hhpzZvT7V/3uBgY9S8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782201607; c=relaxed/simple; bh=5RIuw2MEHxSHGVcI5kUi/FL8Cbc9th4E1WezN8FfOes=; h=Subject:Cc:Date:Message-Id:Mime-Version:Content-Type:To:From; b=BZwdbXvI8RcfLKUB+4m4ibToJ1rKpRgXeN83h22Vp1EKLbKeBE7a3bBFmbQFhHhN2bHsiuADSC4yuUWPEGWwVReSjIBKPAtuBUJ+jjGp/InBSKFb89YSgh4RmZcjnwZ+gSpZtSpMG59uqJptZXuMCp8/Cpl6A7KOfonSIipmBhQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fnnas.com; spf=pass smtp.mailfrom=fnnas.com; dkim=pass (2048-bit key) header.d=fnnas-com.20200927.dkim.feishu.cn header.i=@fnnas-com.20200927.dkim.feishu.cn header.b=iJyJctB/; arc=none smtp.client-ip=209.127.231.38 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fnnas.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fnnas.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fnnas-com.20200927.dkim.feishu.cn header.i=@fnnas-com.20200927.dkim.feishu.cn header.b="iJyJctB/" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=s1; d=fnnas-com.20200927.dkim.feishu.cn; t=1782201593; h=from:subject:mime-version:from:date:message-id:subject:to:cc: reply-to:content-type:mime-version:in-reply-to:message-id; bh=TY24S4uu8LrOjylO1lyti0tMLPua4FxRHUW/K6E/Wbk=; b=iJyJctB/pmCGU/4yiWhk2ccmtFxFBcY8DAz7BUnGBmvcadjB4fW3ZJwa+PkazhXSk3qNJ5 4Qqh6HZTE8YyKkW8lN/kHmeNBg6EWav1kZUntXGMxDp0XX92nzNOdsFkUVsi0vOvhVykZG 5HmwlBfjQhspVkQyKx7U0/Y4cUFaU9Pu4ZJR/BvdcUVOfgXR2zb6M8jW1pG5F1Zo8QIJu3 e+qOpPxVLUqwbeZsGW+jjCHOtHjFckBh4KPQTVddoJNx6uxNZnLzcjPd+GN+HVceKEehu1 VVywCyRePysh/64kLrfLBzSWepqqroRaz3XiEvMnRjed+/AJl+x78KJhWwe/Zw== Subject: [PATCH] md/raid1: protect sequential read hints for read balance X-Original-From: chencheng@fnnas.com Cc: , Date: Tue, 23 Jun 2026 15:59:40 +0800 Message-Id: <20260623075940.2476255-1-chencheng@fnnas.com> Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Lms-Return-Path: X-Mailer: git-send-email 2.54.0 Content-Type: text/plain; charset=UTF-8 To: , , From: "Chen Cheng" Content-Transfer-Encoding: 7bit Received: from localhost.localdomain ([183.34.170.156]) by smtp.feishu.cn with ESMTPS; Tue, 23 Jun 2026 15:59:50 +0800 From: Chen Cheng The patch just suppress KCSAN noise. No functional change. KCSAN reports a race, point to update_read_sectors() update next_seq_sect vs. read next_seq_sect. Protect next_seq_sect and seq_start with READ_ONCE/WRITE_ONCE, otherwise, read balance see stale sequential-read hints. KCSAN report: ============== BUG: KCSAN: data-race in raid1_read_request / raid1_read_request write to 0xffff8e3a2d6736d0 of 8 bytes by task 593784 on cpu 10: raid1_read_request+0xe5a/0x19f0 raid1_make_request+0xdf/0x1990 md_handle_request+0x4a2/0xa40 [...] read to 0xffff8e3a2d6736d0 of 8 bytes by task 593776 on cpu 11: raid1_read_request+0xe3f/0x19f0 raid1_make_request+0xdf/0x1990 md_handle_request+0x4a2/0xa40 [...] value changed: 0x0000000000356368 -> 0x0000000000356370 Signed-off-by: Chen Cheng --- drivers/md/raid1.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 4cdf4484cab6..29b58583e381 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -602,13 +602,13 @@ static void update_read_sectors(struct r1conf *conf, int disk, sector_t this_sector, int len) { struct raid1_info *info = &conf->mirrors[disk]; atomic_inc(&info->rdev->nr_pending); - if (info->next_seq_sect != this_sector) - info->seq_start = this_sector; - info->next_seq_sect = this_sector + len; + if (READ_ONCE(info->next_seq_sect) != this_sector) + WRITE_ONCE(info->seq_start, this_sector); + WRITE_ONCE(info->next_seq_sect, this_sector + len); } static int choose_first_rdev(struct r1conf *conf, struct r1bio *r1_bio, int *max_sectors) { @@ -733,31 +733,33 @@ static int choose_slow_rdev(struct r1conf *conf, struct r1bio *r1_bio, return bb_disk; } static bool is_sequential(struct r1conf *conf, int disk, struct r1bio *r1_bio) { - /* TODO: address issues with this check and concurrency. */ - return conf->mirrors[disk].next_seq_sect == r1_bio->sector || + return READ_ONCE(conf->mirrors[disk].next_seq_sect) == r1_bio->sector || READ_ONCE(conf->mirrors[disk].head_position) == r1_bio->sector; } /* * If buffered sequential IO size exceeds optimal iosize, check if there is idle * disk. If yes, choose the idle disk. */ static bool should_choose_next(struct r1conf *conf, int disk) { struct raid1_info *mirror = &conf->mirrors[disk]; + sector_t seq_start, next_seq_sect; int opt_iosize; if (!test_bit(Nonrot, &mirror->rdev->flags)) return false; opt_iosize = bdev_io_opt(mirror->rdev->bdev) >> 9; - return opt_iosize > 0 && mirror->seq_start != MaxSector && - mirror->next_seq_sect > opt_iosize && - mirror->next_seq_sect - opt_iosize >= mirror->seq_start; + seq_start = READ_ONCE(mirror->seq_start); + next_seq_sect = READ_ONCE(mirror->next_seq_sect); + return opt_iosize > 0 && seq_start != MaxSector && + next_seq_sect > opt_iosize && + next_seq_sect - opt_iosize >= seq_start; } static bool rdev_readable(struct md_rdev *rdev, struct r1bio *r1_bio) { if (!rdev || test_bit(Faulty, &rdev->flags)) -- 2.54.0