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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7924C109316E for ; Fri, 20 Mar 2026 03:14:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DEB916B0420; Thu, 19 Mar 2026 23:14:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DC2286B042E; Thu, 19 Mar 2026 23:14:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CFFFE6B042F; Thu, 19 Mar 2026 23:14:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id BEDC76B0420 for ; Thu, 19 Mar 2026 23:14:37 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 6AE078C53F for ; Fri, 20 Mar 2026 03:14:37 +0000 (UTC) X-FDA: 84564973794.27.E5E2DF3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf12.hostedemail.com (Postfix) with ESMTP id C5AE840006 for ; Fri, 20 Mar 2026 03:14:35 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=o1wA1ZmS; spf=pass (imf12.hostedemail.com: domain of akpm@linux-foundation.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1773976475; 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:dkim-signature; bh=aVJQbKEfor+RxmQcFK97BTwdfEIJFHktsF6U5NupqIo=; b=ff9BhAQKkKapbbNgzJTr68ESsPFuA0o3TSl2sX9zy+8LzWF1JYTzfG1DaFYfxLLKIU3lzb YZm7adqi+MnGfq63vk52hh1ABDS+snaibvT3sGcKGDRBSEcbOHrKQVewsD+YFYAj1pm3Ee imvbp+HCxIMADrd95I5FdkyZ8xOJttU= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=o1wA1ZmS; spf=pass (imf12.hostedemail.com: domain of akpm@linux-foundation.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1773976475; a=rsa-sha256; cv=none; b=kL9TqHRXw3ysilfmE5l/PdMS80SAZ8/mH1WDEb5LjcwK8XgLeirw82VztYof370zjkj0g2 sEXvlKwMAdXGsG+LAI4clj5G39RHGyytJohJgpOBqq0rUNING2T1aUUCVFwIbJb1nJYiCk lE3xJberD7OcoT3bK/jwazNl+ilJsWo= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 12FCF60097; Fri, 20 Mar 2026 03:14:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96F43C19424; Fri, 20 Mar 2026 03:14:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1773976474; bh=1ldpoIJJPrstSo7P+uHcHJMsXGhDf6QFzETNfcD8JmU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=o1wA1ZmS2n1U/a7/+G5dzNWCWW02PcdZ1i1f1hnH4Yx/UFtzuij7AxCt9D/7vunfK RYMQ5fgggQVSL/sesJzy7eFjfAzbwzfHbTpbwfm8C6fzywK1xCK3d/8K9JKQjB8lZB M/aa0TN73tcSF97ejcTfl9m+9LcYyg7blP1FQzAI= Date: Thu, 19 Mar 2026 20:14:34 -0700 From: Andrew Morton To: Hao Ge Cc: Suren Baghdasaryan , Kent Overstreet , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/alloc_tag: clear codetag for pages allocated before page_ext initialization Message-Id: <20260319201434.b51833a0fea2801a2b220ee5@linux-foundation.org> In-Reply-To: <20260319083153.2488005-1-hao.ge@linux.dev> References: <20260319083153.2488005-1-hao.ge@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: C5AE840006 X-Stat-Signature: tien5c759ns97u78p8k1jxioim4wfk3a X-Rspam-User: X-HE-Tag: 1773976475-282308 X-HE-Meta: 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 y97f/glk v7oAaNrs9vanlhp6WI8KwCxu+QyNdGzHuzsUJf18ylawUuN4Pmrn2ID18mbdXPlnRHsD+kKd6P8hC0UCZsNqzGNBT+jx8EMUb3h9JRNYSfVi2KIqcekzM4tEeDhZU5jFPPGWR7m5YgCejvmooeNBuf3pVD+780q5+nwm2sNMNXNYGJhDNhsTQpU2AEKSoMLJXOl5UXFWPjax++9euRW7oh4aBuO8d5nXudtHZq8v0xdu+a6pvIptbxFf42MxSFt5wHU0ru4vGYhqnfhHi2efYiMXhoVf/wK8silhzA7QgNZMW0utfieDzvXi1X44m9vd34dmac0q9A5rzI+GDtGSkMC3C8lH+Lj0Ck4I+ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 19 Mar 2026 16:31:53 +0800 Hao Ge wrote: > Due to initialization ordering, page_ext is allocated and initialized > relatively late during boot. Some pages have already been allocated > and freed before page_ext becomes available, leaving their codetag > uninitialized. > > A clear example is in init_section_page_ext(): alloc_page_ext() calls > kmemleak_alloc(). If the slab cache has no free objects, it falls back > to the buddy allocator to allocate memory. However, at this point page_ext > is not yet fully initialized, so these newly allocated pages have no > codetag set. These pages may later be reclaimed by KASAN,which causes > the warning to trigger when they are freed because their codetag ref is > still empty. > > Use a global array to track pages allocated before page_ext is fully > initialized, similar to how kmemleak tracks early allocations. > When page_ext initialization completes, set their codetag > to empty to avoid warnings when they are freed later. AI review asks questions: https://sashiko.dev/#/patchset/20260319083153.2488005-1-hao.ge%40linux.dev