From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 E70CB3FB1B for ; Sun, 28 Jul 2024 13:41:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722174075; cv=none; b=imGf6jjIb8gxbmNRofRlZM+hAJcPDoX2bIjS+Y0XehbpdUV/ScHbf1snkgCr/YEOZ29hklfE3aFcEOd04FZmysCriF4j89pZ6ftMDQMcMBqi0ylJj1Zjv5A25hXRoo7EhKMAd77sJG6Wwrgg39BA/Wr3PJk85tOMysv5MJyMo5Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722174075; c=relaxed/simple; bh=wb4+K2jfFCFJm7Q0XiElSQSTmr+5cRu6tJRMaxHh720=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WX2gx18okiEgXbmFoLGdhbn40X0J3aTcUGOG/bT9M9umNu6Sev4Z0nrsdACxyT+CJskjrSmF/vsJPM8pUDDG7ZVDdfQOXonUZFYGBRI1gZ4Zh/vNl7e7/1hFCCfYem801Z+6W8uBJBoHjHvv0xsYCwrqAP6Ab+23VERK06bf+2Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=X7sFfT1C; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="X7sFfT1C" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722174070; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XJS8UcnJOB/j9GcsBVriXkTBQzfHbx96+YQU+0aGTwY=; b=X7sFfT1CjTT0Q1lkpWzRVDdZvGpIE5T7phSqNf9uq1zywv91OR7HROIhOe+UY7bpBAFk4m L2fYWVchwYhQGI+9AxVTKwzq7z16InRt6VnVIOuW/uYG9JL2go2u+RnBHO24/yqj2iE9gj 8NaLLAFFSwJitLiLzyLFgzxdxr2UUT8= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-104-KazrzR4NO8y_Q0he9wBSug-1; Sun, 28 Jul 2024 09:41:06 -0400 X-MC-Unique: KazrzR4NO8y_Q0he9wBSug-1 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 04F3B1955D45; Sun, 28 Jul 2024 13:41:05 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.13]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 36239300018D; Sun, 28 Jul 2024 13:41:01 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Sun, 28 Jul 2024 15:41:05 +0200 (CEST) Date: Sun, 28 Jul 2024 15:41:01 +0200 From: Oleg Nesterov To: Mateusz Guzik , Hillf Danton Cc: paulmck@kernel.org, Christian Brauner , rcu@vger.kernel.org Subject: Re: rcu_sync_dtor() warning question Message-ID: <20240728134101.GA8691@redhat.com> References: <20240726-ansonsten-piste-c4f04d4909fc@brauner> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Sorry for late reply. You do not need my help, I know nothing about fs ;) but just in case... On 07/26, Mateusz Guzik wrote: > > Welp. > > syzbot did the bisect, it's not any of the above, instead: > > commit b62e71be2110d8b52bf5faf3c3ed7ca1a0c113a5 > Author: Chao Yu > Date: Sun Apr 23 15:49:15 2023 +0000 > > f2fs: support errors=remount-ro|continue|panic mountoption > > https://lore.kernel.org/linux-fsdevel/0000000000004ff2dc061e281637@google.com/T/#m90c03813e12e5cdff1eeada8f9ab581d5f039c76 > > That said, the stuff I mentioned still looks highly suspicious so I > have to something to investigate regardless. Did you see the patch from Hillf ? https://lore.kernel.org/all/20240727011616.2144-1-hdanton@sina.com/ it seems to fix the problem... Of course I don't understand this patch, but afaics SB_RDONLY can confuse thaw_super_locked(). If sb_rdonly() is true, thaw_super_locked() assumes that freeze_super() didn't call sb_wait_write() -> percpu_down_write(). So in this case thaw_super_locked() just clears sb->s_writers.frozen and goes to the "out_deactivate" label bypassing sb_freeze_unlock(). Oleg.