From nobody Mon Apr 13 17:14:29 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0AA0C433FE for ; Tue, 15 Nov 2022 16:49:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231853AbiKOQtq (ORCPT ); Tue, 15 Nov 2022 11:49:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230245AbiKOQtm (ORCPT ); Tue, 15 Nov 2022 11:49:42 -0500 Received: from mail-pg1-x52a.google.com (mail-pg1-x52a.google.com [IPv6:2607:f8b0:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3354A1A220 for ; Tue, 15 Nov 2022 08:49:40 -0800 (PST) Received: by mail-pg1-x52a.google.com with SMTP id b62so13814793pgc.0 for ; Tue, 15 Nov 2022 08:49:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=to:cc:date:message-id:subject:mime-version :content-transfer-encoding:from:from:to:cc:subject:date:message-id :reply-to; bh=/sFPJMhL4zQAK/mKWhLbds2x5kABYr2ZkNwW8lGz7fQ=; b=LI1Y4dmrZ2qUaT5Be+eQi5GvLXg5LGquqTNlXqRX3gv2Ao+imEpKsrgnN6xMfvjmJW pg6woE2NcYs1cNYIbG7/DuG/r6eHxn5uiVcN9wmDPER1GMCrKFGdsWmpSVk46qLeF1Fm DbWioojc69dejvOy/u6cbDkn7yl1kAtZJNtexpkOePvBPZG1C7ZYvRJkdVuhz1NlVR+z w7leGp2ADRqrm3+A4fTZF4bA4cc3hyNg9EBKGc6kIByMnH+3q8OjeEOF2MtV1wd57olO hSNTtXCXxrEjpxr7njlqJoz7t2xsO6PF/cnzKJYix7nhcmSjdU+0h61BCfVyhtw87oA1 PRCw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=to:cc:date:message-id:subject:mime-version :content-transfer-encoding:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=/sFPJMhL4zQAK/mKWhLbds2x5kABYr2ZkNwW8lGz7fQ=; b=TjR3PMMchXGSymvmk85l5/WTWSlLsflvrT4I0V2kIz+jthKYSbvXfXtDwRuM9ieMTN JMFbn/wHmU/xF3A+NRsaLumKHau8BERwmoDI9sMu44eTM0tSIIoe/q8rlaEh9iTTObma 0ejFKzUggB107DFo2YvE5/NoIuk1ZL6f7gXOdqde7CKtNU2a/Wu6MFC1evuZbL6oYjVt jgNg7y34eUD6jgU7laLrZHAZrRaq63e2OlK84lJZMwK4efSe+6pNjmy+Dtiw4setdhU+ LtoXAocCaseLLbec8YYXALi/N4Fwm5LCZ7PlMxwRkaKEIlrBzMhs5XWt8PDEmESoIoNn VVhw== X-Gm-Message-State: ANoB5pliyTT/ua6ybFeDBMHn2UTBWraLpNL1bdsWdSDBZF0LwsYvP9fg zH2lbPayK4uDGrZ6qFYUUoo= X-Google-Smtp-Source: AA0mqf7q0LeWm3ohS3v+L4cwu2FwSthe2H0q3FclrVCanxfQDidmZ9kwV0I57K9V3dgKdDy/W8CHIg== X-Received: by 2002:a63:5348:0:b0:456:d859:2145 with SMTP id t8-20020a635348000000b00456d8592145mr16867756pgl.56.1668530979561; Tue, 15 Nov 2022 08:49:39 -0800 (PST) Received: from smtpclient.apple ([103.135.102.120]) by smtp.gmail.com with ESMTPSA id a13-20020a170902eccd00b0017f9db0236asm10251511plh.82.2022.11.15.08.49.36 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 15 Nov 2022 08:49:38 -0800 (PST) From: =?utf-8?B?6buE56eL6ZKn?= Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.80.82.1.1\)) Subject: [PATCH -next]pstore/zone: Preallocate zone buffer for psz_kmsg_write_record Message-Id: Date: Wed, 16 Nov 2022 00:49:33 +0800 Cc: WeiXiong Liao , anton@enomsg.org, ccross@android.com, tony.luck@intel.com, LKML To: keescook@chromium.org X-Mailer: Apple Mail (2.3696.80.82.1.1) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The case found when triggering a panic_on_oom, pstore fails to dump kmsg. Partly fixed by: commit 99b3b837855b ("pstore/zone: Use GFP_ATOMIC to allocate zone buffer"). After the patch, it also fails sometimes. As I use 64k as kmsg_size, it's hard to get 4-order free pages sometimes at this case. So it's better to preallocate the buffer. Signed-off-by: Qiujun Huang --- fs/pstore/zone.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/fs/pstore/zone.c b/fs/pstore/zone.c index 2770746bb7aa..86e47dbc9d53 100644 --- a/fs/pstore/zone.c +++ b/fs/pstore/zone.c @@ -136,6 +136,7 @@ struct psz_context { struct mutex pstore_zone_info_lock; struct pstore_zone_info *pstore_zone_info; struct pstore_info pstore; + struct psz_buffer *kmsg_buf_swap; }; static struct psz_context pstore_zone_cxt; =20 @@ -758,14 +759,11 @@ static inline int notrace psz_kmsg_write_record(struc= t psz_context *cxt, if (unlikely(!zone)) return -ENOSPC; =20 - /* avoid destroying old data, allocate a new one */ + /* avoid destroying old data, use the swap buffer */ len =3D zone->buffer_size + sizeof(*zone->buffer); zone->oldbuf =3D zone->buffer; - zone->buffer =3D kzalloc(len, GFP_ATOMIC); - if (!zone->buffer) { - zone->buffer =3D zone->oldbuf; - return -ENOMEM; - } + zone->buffer =3D cxt->kmsg_buf_swap; + memset(zone->buffer, 0, len); zone->buffer->sig =3D zone->oldbuf->sig; =20 pr_debug("write %s to zone id %d\n", zone->name, zonenum); @@ -776,15 +774,14 @@ static inline int notrace psz_kmsg_write_record(struc= t psz_context *cxt, if (likely(!ret || ret !=3D -ENOMSG)) { cxt->kmsg_write_cnt =3D zonenum + 1; cxt->kmsg_write_cnt %=3D cxt->kmsg_max_cnt; - /* no need to try next zone, free last zone buffer */ - kfree(zone->oldbuf); + /* no need to try next zone, put last one to swap buffer */ + cxt->kmsg_buf_swap =3D zone->oldbuf; zone->oldbuf =3D NULL; return ret; } =20 pr_debug("zone %u may be broken, try next dmesg zone\n", zonenum); - kfree(zone->buffer); zone->buffer =3D zone->oldbuf; zone->oldbuf =3D NULL; } @@ -1373,6 +1370,12 @@ int register_pstore_zone(struct pstore_zone_info *in= fo) err =3D -ENOMEM; goto fail_free; } + + cxt->kmsg_buf_swap =3D kzalloc(info->kmsg_size, GFP_KERNEL); + if (!cxt->kmsg_buf_swap) { + err =3D -ENOMEM; + goto fail_free; + } } cxt->pstore.data =3D cxt; =20 @@ -1411,6 +1414,8 @@ int register_pstore_zone(struct pstore_zone_info *inf= o) return 0; =20 fail_free: + kfree(cxt->kmsg_buf_swap); + cxt->kmsg_buf_swap =3D NULL; kfree(cxt->pstore.buf); cxt->pstore.buf =3D NULL; cxt->pstore.bufsize =3D 0; @@ -1445,6 +1450,9 @@ void unregister_pstore_zone(struct pstore_zone_info *= info) flush_delayed_work(&psz_cleaner); =20 /* Clean up allocations. */ + kfree(cxt->kmsg_buf_swap); + cxt->kmsg_buf_swap =3D NULL; + kfree(cxt->pstore.buf); cxt->pstore.buf =3D NULL; cxt->pstore.bufsize =3D 0; --=20 2.30.2