From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=115.124.30.98 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794298778; b=XmA9qp8GZo5VZrs+9jz9hwu5wiLok2WH3QLYagkkQ1mGhINfb3RT9Dj9IsOT3kW89Wod k6/m676FmX3ax3bXfktrauNIh4In6/uvpmBeXAgngp+9tFjOfGkzUbLlE/honlNSN+iuF GACWOrCtsWE+y8ju2v1wEgNA3sCHFPb9UVkmCdKTYmihKOPvv2Yi8Z0SFME5D9W/ypysA G7UcuJnrC49I1GySjBW0DNi0K3JqNQmBjuXrGP18VUBqvo/83/+V9YSqof5Wqip46Jw62 jbYc3zlptH/+9c+h/WWW2gLd3LgArxgujwSIcMLnMOvDzsSh+VCEYDmOFDgqFIrLy2Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794298778; h=DMARC-Filter:DKIM-Signature:X-Alimail-AntiSpam:Received:From:To:Cc: Subject:Date:Message-ID:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=jHh8QP5RizpiZ/rOn8/fPhqoJKsZVAfXdzIBsu2Zprc=; b=eIDHZ8MyxQa/hLrTR5yumUcBKn8YQy1ICf1Bbz1dcGrFy8/xG9gmwFfW+aLKBVFAgveB YQIHEktO1X3VslflwVRE9MMBF3mr28MaSJJCpPoe1Cben2YnuTirSOr/Qf2wURxvljCC3 l7aOICasieMGhgPMWA+e0GEf9Uu2YysBTKRoPpbhfherd+So+oZN/WM6BDl2tu4f4yUlJ ba/nWgcYrmQNUiqnL04sXb/aL/mMNHSYjlT+3EkUp34rtyS0VJjlLEUPHWKKyp8bn8mlH Dj5JsKwGI5GzDLLOgu2E8mxwqVY61gSVGwtN7m9SetuoJKHaKL9KQ6g3g9oO9AHsi5Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b=oirsN4Sz; arc=none smtp.remote-ip=115.124.30.98 Received: from out30-98.freemail.mail.aliyun.com (out30-98.freemail.mail.aliyun.com [115.124.30.98]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF066606A31C for ; Tue, 10 Nov 2026 08:19:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org DF066606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b=oirsN4Sz DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1794298774; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=jHh8QP5RizpiZ/rOn8/fPhqoJKsZVAfXdzIBsu2Zprc=; b=oirsN4Szv5wSU9MpqgtBIrQkbdqRzertWo4NV9jIcIrZPZp0ZWK3NDmvQM15cuVK8szTEcq3iUw1NPE+V3wd+C1YGaWsjDvc1Kpt0jEGzKdPusXGpADcvhPkngBsCeuUl0Z1OkWyRC3Aozt/mByOyz9sgmvcqKFHgN7ExCwyHjY= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R511e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033032089153;MF=tongweilin@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0XEUf1sP_1794298765; Received: from x31l07246.sqa.na131.tbsite.net(mailfrom:tongweilin@linux.alibaba.com fp:SMTPD_---0XEUf1sP_1794298765 cluster:ay36) by smtp.aliyun-inc.com; Tue, 10 Nov 2026 16:19:34 +0800 From: Weilin Tong To: Andrew Morton Cc: Weilin Tong , Catalin Marinas , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] mm: kmemleak: avoid long RCU read-side sections in reports Date: Tue, 10 Nov 2026 16:18:25 +0800 Message-ID: <20261110081828.2446101-1-tongweilin@linux.alibaba.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: <20261109211709.133122f9f10091f06c4acbc1@linux-foundation.org> References: <20261109211709.133122f9f10091f06c4acbc1@linux-foundation.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Andrew, Thanks for the review. Yes, this was observed while reading /sys/kernel/debug/kmemleak on our downstream distribution's 6.6-based debug kernel, without injected delays. Here are excerpts from the original log: [1023772.105996] rcu: INFO: rcu_preempt self-detected stall on CPU [1023772.152485] rcu: (t=65047 jiffies g=357990333 q=711371 ncpus=96) [1023772.491019] get_object+0x1e/0x70 [1023772.501186] kmemleak_seq_next+0x91/0xe0 [1023772.512982] seq_read_iter+0x482/0x1160 With CONFIG_HZ=1000, the grace period had lasted about 65 seconds. I should have included this evidence in the cover letter. You're right about *pos: it does not advance when get_object() fails, so an unaligned position can miss the periodic checks throughout the skip loop. Our deleted-chain tests checked safety, but missed this progress issue. I'll address this in v2, preserving safe traversal across concurrent deletion, and add targeted coverage for this case. Thanks, Weilin