From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELtSW7WMtEbdaRCG/uN25EKFGs07juCsuivoAoWBCBBgca8pWnTHQzSoUahIhjDTBPcaFAIQ ARC-Seal: i=1; a=rsa-sha256; t=1520641373; cv=none; d=google.com; s=arc-20160816; b=b+wHhw8yFlR7G7eAGiMLU/y0uHgdInUz+e8YfgWFv7JxnuoAoi9OHcz258CwkRG0Wd fMwCte4EeE8H+bvp58u+UAclLHb4vwuUFNKCHG7gZKH/seN8GHuhpQ39YAATj6nmEcZT 2flFIpLU5iKAZhzWIYZf/E5Uqkt2b2BdebjycskALtUXWv3Wk4x+mbsWxWH/2EMhjkB5 GqGucvzXP9ECVhDWqED3y8cBEzwWyUlflDjFPHTZ2eIj8zBu0LOgscDmOMsPljjWsNTo zIJC83ptu6iGjL/i4JUsyEt7U9z6lzEqCsMVhQGiD05SSpfjbQTlLUu/ZawtcutmSobh w9cg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=Sy+BIoF1s7n1YtezsJli0XEZsCjPBmnHDP7BexnBqB4=; b=wgrEP6wJyObDjAvbq+yvjoXatWRqKrJgMQYvv1lZspS1bG/aonoKw5A+a0GpDv+Gvq jYDFCN0gIvopCpVyq0U/CzJCcvG4XB5MeIypaPBYzoGfKwbLIFbM9IjOmZcV2dvM14HR pz6RA6BAaQSIrjUnIYAJKp0rkGTtODdKp4/k92pxAWkIHtuT/trEVbDDvzfcJ1SDhev6 q1LU7VHCkyFiZ98UybxaImKXR1rtTsn8YV5BzyPUy7JFcdI6noANVIAo4Wc3Bvk7mPHQ 0w/0k4l7G0dTvEZE+g4bENF5O5YJVbHua7UESTxUU3V4Jq2cacwKbRYsmrDPMbIAn7gR yxKA== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 185.236.200.248 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 185.236.200.248 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, yuyufen , Tomasz Majchrzak , stable@ver.kernel.org ("v4.8+"), NeilBrown , Shaohua Li Subject: [PATCH 4.9 30/65] md: only allow remove_and_add_spares when no sync_thread running. Date: Fri, 9 Mar 2018 16:18:30 -0800 Message-Id: <20180310001827.315883030@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180310001824.927996722@linuxfoundation.org> References: <20180310001824.927996722@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1594508049522327490?= X-GMAIL-MSGID: =?utf-8?q?1594508049522327490?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit 39772f0a7be3b3dc26c74ea13fe7847fd1522c8b upstream. The locking protocols in md assume that a device will never be removed from an array during resync/recovery/reshape. When that isn't happening, rcu or reconfig_mutex is needed to protect an rdev pointer while taking a refcount. When it is happening, that protection isn't needed. Unfortunately there are cases were remove_and_add_spares() is called when recovery might be happening: is state_store(), slot_store() and hot_remove_disk(). In each case, this is just an optimization, to try to expedite removal from the personality so the device can be removed from the array. If resync etc is happening, we just have to wait for md_check_recover to find a suitable time to call remove_and_add_spares(). This optimization and not essential so it doesn't matter if it fails. So change remove_and_add_spares() to abort early if resync/recovery/reshape is happening, unless it is called from md_check_recovery() as part of a newly started recovery. The parameter "this" is only NULL when called from md_check_recovery() so when it is NULL, there is no need to abort. As this can result in a NULL dereference, the fix is suitable for -stable. cc: yuyufen Cc: Tomasz Majchrzak Fixes: 8430e7e0af9a ("md: disconnect device from personality before trying to remove it.") Cc: stable@ver.kernel.org (v4.8+) Signed-off-by: NeilBrown Signed-off-by: Shaohua Li Signed-off-by: Greg Kroah-Hartman --- drivers/md/md.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8224,6 +8224,10 @@ static int remove_and_add_spares(struct int removed = 0; bool remove_some = false; + if (this && test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) + /* Mustn't remove devices when resync thread is running */ + return 0; + rdev_for_each(rdev, mddev) { if ((this == NULL || rdev == this) && rdev->raid_disk >= 0 &&