From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f182.google.com (mail-yw1-f182.google.com [209.85.128.182]) (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 245BC377020 for ; Mon, 11 May 2026 13:44:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778507052; cv=none; b=mqbKf7HzSkuzdLhX69CZcBV3JxIfK1dQ6FHVtlW7+jiCaxpLBnf/BOC6eiHYFwm31E4Z1G81ANgomVcw4wAN3MqO4Y0TxvVRXWOJvGWn6ymu+PBKyYY/++lVJXZaxgNX1qdfVxiEk7D77oLdkxrSzyI0ZN+HuhfiDSxfTsKU4d4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778507052; c=relaxed/simple; bh=UehvZ/hXVOhpeTqqgpVpTrWVDFONRE8Wt7C+GZ7aKhw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cipEKPTUQbcDkPaFbws1dUBZZw4g3zo3EtaBSktaJZeNxIsLzMioFNimXpvU+eeaQ2rEHXH7OFLFhaSJOxKB4q8cBnrSB1+f9epjxj5gVRnpA892Q7Sgo6SHXcJbrNVOr3XH2k/g/xONgI7QHCGZ+c6I4jXgkdnLvH9gdXMV0yc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=soleen.com; spf=pass smtp.mailfrom=soleen.com; dkim=pass (2048-bit key) header.d=soleen.com header.i=@soleen.com header.b=czJza5Tg; arc=none smtp.client-ip=209.85.128.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=soleen.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=soleen.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=soleen.com header.i=@soleen.com header.b="czJza5Tg" Received: by mail-yw1-f182.google.com with SMTP id 00721157ae682-7bdf83185bbso43328967b3.2 for ; Mon, 11 May 2026 06:44:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen.com; s=google; t=1778507050; x=1779111850; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=WdZp73JFANv1yjTZ6h8yU8Y68BeneeXC5aWjngszTTg=; b=czJza5Tg7lzPUXHYkz6wUBwBaLQv85dtPOr8sjePJJmvrtO0ySO+qWjGkwjnZxfTv4 VgnFX4aaUtAWEs0QbU4HQuwRZ437r4QJj6EnI4B5Sz4Bry151bW1smUlZd6Phr/LegnG XxElipfQVPy8EJ7H/WxJnqGXr182o3VS2k8/KXKJYWu2xvFe7y7Kq6vKBbXU3oneh8tn 73ecTf5RfGxctNDhIIajubag09PQv7qldvgTomiT9gcRX4I8c3z7Q3ruKSiUvD4XIxBI b56XUZqX9ulJ73UOTQwvs/Q4qbB5XZpL1Hp7J65Jg1CXGkE1HccXzMe8FYL1K3wM1tot SW/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778507050; x=1779111850; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=WdZp73JFANv1yjTZ6h8yU8Y68BeneeXC5aWjngszTTg=; b=j5/LnczZ8IHJZ2VTq8q3nOVkSKAdHmzPT2o2gv/sib4t6YCC44nEZPTRlJvqhAAl0Q xO/6SqT8Mh+WvQ6RM8kO3OE+SBGolYwooPd1AElW00aTGL0641GGJGyrZ8O06qkxHeSZ Lh9KUCu8rV8Xa1KbV28y+e2NHrgfypX2BH9O3dNzXe17F6lpE1+4lCVXcyEJBad4JjI7 WXuPvyXauojdIK646FyDhoEQrQfvYalxadu/8zqNrOnEedHYosR9Du153/VPfJpHKfX5 ZFV/mAVDKuTYTMNb/ZHU4dsSiH5o1RTbiH6agYsDAoT2T5uMilqOnoWxD5cS3u2xIeLr rQkg== X-Forwarded-Encrypted: i=1; AFNElJ/t/Gkob91wX98lpw8/A3F46fHeToRt0YhUdnBpt1jCEcr/eXzKzHoJEW+4+avq3ezncDjegJLOYy+DsOA=@vger.kernel.org X-Gm-Message-State: AOJu0YxTo5siwEKjOLibcD4MMcVYGK/0wbz9xt4y65/38fx9sQPBdKEl w/ARSC9bdSSUVT0lMbh00TLuZaelUOfQhZQE9mf+mAHtV8R89OAAct/HpGm2g6LzOn4= X-Gm-Gg: Acq92OGve2Yo3w6bdu+0BtpacTJsfIkAOidFr91Z+kqL1ANTBzokmsemTsFgeQIh0xu ESfAbP5A59DRRTGdobFaFDmirla02fGiTjcn71BJLIWCjAkqNfSSWmB7cGJ1U1rObil3qWgP/CL r84zpDfvkffAxSAmnYq1liIVb67ZA4DdiA85qBl+JsPLmICMc3q762oHi8FhT+qKnw607kn6qD7 i+JhSr02/uI67MTKNJ95Dx5e41veB5CiOjHCi2kmQl6WHAArgGQhBrTWtdwvKyMGu3+/mFzDnP0 7srUT0FSAMaiOIFR6ZZe2oOb4/5f969dkbj4xsCf8OpvFVl2N0vnPdnOAxOgDxZQIkOBhVcBokq EhTKqIWWnv3QGugl2ku3VWK/ho93G2H9CCt+mCKm8BpE/hbJWIVj4UqVT+GsicfFSwZR+P0sPYe nuSVL748VMmxwokRuZB17JSVjlV33m+QpIpDG8cWdwZrgG/7SpUuGAt6qcLwKaaQMSMt9Wt4yoE 7NQs2LewQPAGM7+ZTrx9Kk9g9FS50uYCrZm+A3HZmY= X-Received: by 2002:a05:690c:3482:b0:7ba:eefe:9f9c with SMTP id 00721157ae682-7bfb93b91bfmr134951057b3.23.1778507049874; Mon, 11 May 2026 06:44:09 -0700 (PDT) Received: from google.com (138.200.150.34.bc.googleusercontent.com. [34.150.200.138]) by smtp.gmail.com with ESMTPSA id 00721157ae682-7bd6686ead7sm150263157b3.39.2026.05.11.06.44.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 May 2026 06:44:09 -0700 (PDT) Date: Mon, 11 May 2026 09:44:08 -0400 From: Pasha Tatashin To: Pratyush Yadav Cc: Pasha Tatashin , rppt@kernel.org, sourabhjain@linux.ibm.com, jbouron@amazon.com, akpm@linux-foundation.org, linux-mm@kvack.org, bhe@redhat.com, linux-kernel@vger.kernel.org, dan.carpenter@linaro.org, rafael.j.wysocki@intel.com, piliu@redhat.com, kexec@lists.infradead.org, graf@amazon.com, changyuanl@google.com, mario.limonciello@amd.com Subject: Re: [PATCH v2 3/3] liveupdate: block outgoing session mutations Message-ID: References: <20260506182039.2623553-5-pasha.tatashin@soleen.com> <20260506182039.2623553-8-pasha.tatashin@soleen.com> <2vxzv7cucint.fsf@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@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: <2vxzv7cucint.fsf@kernel.org> On 05-11 13:03, Pratyush Yadav wrote: > On Wed, May 06 2026, Pasha Tatashin wrote: > > > During the reboot() syscall, user processes may still be running > > concurrently and attempting to mutate sessions (e.g., adding files or > > closing sessions). To prevent this, hold the session header's rwsem and > > each session's mutex indefinitely on successful serialization. > > > > If serialization succeeds, these locks will never be released as the > > system transitions to the new kernel, effectively blocking any > > concurrent task attempting to modify or release a session. If > > liveupdate_reboot() fails, the locks are released in the error path, > > allowing normal operation to resume. > > > > Fixes: 0153094d03df ("liveupdate: luo_session: add sessions support") > > Reported-by: Oskar Gerlicz Kowalczuk > > Signed-off-by: Pasha Tatashin > > Reviewed-by: Pratyush Yadav (Google) Sashiko also provided a good comment about this patch: We run over MAX_LOCK_DEPTH limit with this patch. I am going to refactor to not take every session lock simultaneously during serialization. > > [...] > > -- > Regards, > Pratyush Yadav