From mboxrd@z Thu Jan 1 00:00:00 1970 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BCBB0EB64DD for ; Fri, 4 Aug 2023 01:44:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 36E5A2802B3; Thu, 3 Aug 2023 21:44:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2F74B2802AE; Thu, 3 Aug 2023 21:44:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 170B92802B3; Thu, 3 Aug 2023 21:44:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 049822802AE for ; Thu, 3 Aug 2023 21:44:38 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id BD0721212A1 for ; Fri, 4 Aug 2023 01:44:37 +0000 (UTC) X-FDA: 81084727794.15.5D8073E Received: from dggsgout11.his.huawei.com (unknown [45.249.212.51]) by imf05.hostedemail.com (Postfix) with ESMTP id 78EF110000C for ; Fri, 4 Aug 2023 01:44:34 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=none; spf=none (imf05.hostedemail.com: domain of thunder.leizhen@huaweicloud.com has no SPF policy when checking 45.249.212.51) smtp.mailfrom=thunder.leizhen@huaweicloud.com; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1691113475; a=rsa-sha256; cv=none; b=xOuVpf4dEIFiXRMeUQ3cJ07z5Odo0AjPRjxsJ/uuBMv/Xk8hNkrM/RKGitVbHmRybAB1uv /G6vlJyJKfOqBH0ZKltkXbdefXSAQc6F6u6LRXWTMMIGdNIiM0W9XUA7pGtOWn1yDU6dzJ lqC7UtZ2My2Cynt+ZXJ0QCbaitzAYH8= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=none; spf=none (imf05.hostedemail.com: domain of thunder.leizhen@huaweicloud.com has no SPF policy when checking 45.249.212.51) smtp.mailfrom=thunder.leizhen@huaweicloud.com; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1691113475; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SHIxjVcz65EpQUEDILqSL3FwquoIub/FoeYd89PE7IA=; b=TFb8rc+C/mzZGcvsEQMKZt06RqkjwtfBOZtVWPQ/cteKozBhqnzNzYXCJG5Wr6Q1AMRBZn GNecD5fXJtLUg/z/IQhL0H0Bnjyv0xH2whHjGVIGkAj2Q4GKvCj231IcmUqv4BeRe0v2RM wIjUiNgMGO01NlilXD6dVODDUwjDEXc= Received: from mail02.huawei.com (unknown [172.30.67.143]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4RH7mq1z9Kz4f3jLx for ; Fri, 4 Aug 2023 09:44:27 +0800 (CST) Received: from [10.174.178.55] (unknown [10.174.178.55]) by APP4 (Coremail) with SMTP id gCh0CgD3X7P6V8xk6Z0MPg--.4994S3; Fri, 04 Aug 2023 09:44:28 +0800 (CST) Subject: Re: [PATCH v5 3/3] mm: Dump the memory of slab object in kmem_dump_obj() To: Vlastimil Babka , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, "Paul E . McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , rcu@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Zhen Lei References: <20230803101754.1149-1-thunder.leizhen@huaweicloud.com> <20230803101754.1149-4-thunder.leizhen@huaweicloud.com> <8a08b7aa-ce1f-4b3d-abb5-cf3191474725@suse.cz> From: "Leizhen (ThunderTown)" Message-ID: <5d625946-28f1-f532-dd58-af18263a8bea@huaweicloud.com> Date: Fri, 4 Aug 2023 09:44:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <8a08b7aa-ce1f-4b3d-abb5-cf3191474725@suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CM-TRANSID:gCh0CgD3X7P6V8xk6Z0MPg--.4994S3 X-Coremail-Antispam: 1UD129KBjvJXoWxZw13Kw4fJrWUZF1UGr45ZFb_yoW5WF4kpr 98Gr1UKrZ7ArnrCrn7X3WDJFnxJ3ykCF1kA3yav3W2vryDXr48uFyktF97uFyrAF1Sq39F yr4qqF9I934UJaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvIb4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6r1S6rWUM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7Mxk0xIA0c2IE e2xFo4CEbIxvr21l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxV Aqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a 6rW5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6x kF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE 14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf 9x07UZ18PUUUUU= X-CM-SenderInfo: hwkx0vthuozvpl2kv046kxt4xhlfz01xgou0bp/ X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 78EF110000C X-Stat-Signature: esbke8fuzfretrfw1bnoj58mwi8pp9nu X-HE-Tag: 1691113474-110048 X-HE-Meta: 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 gR2X29R1 TP5u6nJc7Bj02yqyNVoYdFpfQGeQAH9CMmdiLnIPb6PDt0ov1G43XA99GRxGEzB6H851n4VQ983fpcq7uUBrY4lRm1XCJws38SWejkvGw8aMYAwRBKfiFS4PzW6E7ReAUTnTimJnMnFPdcKRwSzPKTKcDiwZ/MTxdms44+jEI13Pm14ixK/FLDIpDp5NH38SMVQzoGRAI9XT9XesByOfVN5LnPSXa1+rXt3jd0exR911Iih46Mb1uGF+NVMRMaM0ahqmgfAFxhZCR8wzhOgGRUfXLjkCY3+gdTPAscsT+rzfT7R37Jysz+ItUEkBau4RGJeeUfdk/l2hp+KQqEA+FrAcHliZOH1kv7OdbtFNs/WIbfU+0umZdPfej74Bo7MpH3Hu+ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2023/8/3 18:34, Vlastimil Babka wrote: > On 8/3/23 12:17, thunder.leizhen@huaweicloud.com wrote: >> From: Zhen Lei >> >> The contents of the slab object may contain some magic words and other >> useful information that may be helpful in locating problems such as >> memory corruption and use-after-free. >> >> To avoid print flooding, dump up to "16 * sizeof(int) = 64" bytes >> centered on argument 'ojbect'. >> >> For example: >> slab kmalloc-64 start ffff4043802d8b40 pointer offset 24 size 64 >> [8b40]: 12345678 00000000 8092d000 ffff8000 >> [8b50]: 00101000 00000000 8199ee00 ffff4043 >> [8b60]: 00000000 00000000 00000000 00000100 >> [8b70]: 00000000 9abcdef0 a8744de4 ffffc7fe >> >> Signed-off-by: Zhen Lei >> --- >> mm/slab_common.c | 30 +++++++++++++++++++++++++++--- >> 1 file changed, 27 insertions(+), 3 deletions(-) >> >> diff --git a/mm/slab_common.c b/mm/slab_common.c >> index ee6ed6dd7ba9fa5..0232de9a3b29cf5 100644 >> --- a/mm/slab_common.c >> +++ b/mm/slab_common.c >> @@ -553,7 +553,7 @@ static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab * >> bool kmem_dump_obj(void *object) >> { >> char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc"; >> - int i; >> + int i, object_size = 0; >> struct slab *slab; >> unsigned long ptroffset; >> struct kmem_obj_info kp = { }; >> @@ -580,12 +580,36 @@ bool kmem_dump_obj(void *object) >> ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset; >> pr_cont(" pointer offset %lu", ptroffset); >> } >> - if (kp.kp_slab_cache && kp.kp_slab_cache->object_size) >> - pr_cont(" size %u", kp.kp_slab_cache->object_size); >> + if (kp.kp_slab_cache && kp.kp_slab_cache->object_size) { >> + object_size = kp.kp_slab_cache->object_size; >> + pr_cont(" size %u", object_size); >> + } >> if (kp.kp_ret) >> pr_cont(" allocated at %pS\n", kp.kp_ret); >> else >> pr_cont("\n"); >> + >> + /* Dump a small piece of memory centered on 'object' */ >> + if (kp.kp_objp && object_size) { >> + int *p = object, n = 16; >> + >> + p += n / 2; >> + if ((void *)p > kp.kp_objp + object_size) >> + p = kp.kp_objp + object_size; >> + >> + p -= n; >> + if ((void *)p < kp.kp_objp) >> + p = kp.kp_objp; >> + >> + n = min_t(int, object_size / sizeof(int), n); >> + for (i = 0; i < n; i++, p++) { >> + if (i % 4 == 0) >> + pr_info("[%04lx]:", 0xffff & (unsigned long)p); >> + pr_cont(" %08x", *p); >> + } >> + pr_cont("\n"); > > There's a print_hex_dump() for this, see how it's used from e.g. __dump_page(). Thank you very much. The code has suddenly been a lot simpler. However, print_hex_dump() can be further enhanced, I will add a patch, let's discuss it together. > > >> + } >> + >> for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) { >> if (!kp.kp_stack[i]) >> break; > > . > -- Regards, Zhen Lei