From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-67.mta1.migadu.com [95.215.58.67]) (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 E26353B0AE2 for ; Mon, 10 Aug 2026 09:40:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.67 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786354809; cv=none; b=oL1hKddl4VRTYXKw2R4vtqdy3UX2BRg5eFisnShOYzo4H/JKgbFTUbVi/L/uq2Ef+rDO9lHN9Ee3CUvaRY4ptUrG1q8bcWiiwn3VQGf8mIz0f6906gY/DWuIrxkohwROyG8rojJmD1h8eaprZrLQqGxRKOiLy0piUXwFyLuLJnc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786354809; c=relaxed/simple; bh=+7z3AP/ISNgtjS8Lqlp+ZNKMBFC0XbB0Gkd40yGE6eg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=jDQU3Gh6mlQpI/spKUWbRJb4rUXl/g1mp5RlIeS+FpvsyVgqGbpN7tSeTRTzfl6JrLmqL985L1TaAF9uuTqmCOkynRa/lhBYue9/f71H1TC0SjzIJR32Crq1qEEQJgrw5A+KxEwoJUqaBgOO9nk+PeEwz85Ia9bZHw6pLzBLytY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=X6JETdJL; arc=none smtp.client-ip=95.215.58.67 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="X6JETdJL" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=+7z3AP/ISNgtjS8Lqlp+ZNKMBFC0XbB0Gkd40yGE6eg=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786354805; v=1; x=1786959605; b=X6JETdJLrNicIKajmnhxVTliKWjVG6cxTJow4sXQbILvCLiOXKsj1tEzo26qKwfiQ6S8BA+p XBBnPYe9+SwRw28+z938Zw4v/cTGcAmm7fp0KqIWYer0e0+XqfAbf4a71KvR+ElfK9ehdVX+6xJ F49syguUdUm0vLDLSDXRS+OY= X-Envelope-To: linux-kernel@vger.kernel.org Received: from localhost.localdomain (116.128.244.169) by mta10.migadu.com with ESMTPS id 52b4c21b50599e27; Mon, 10 Aug 2026 09:40:05 +0000 X-Migadu-Scanner: mta10.migadu.com Authentication-Results: mta10.migadu.com; none From: Hao Ge To: Suren Baghdasaryan , Andrew Morton , Luis Chamberlain , Petr Pavlu , Daniel Gomez , Sami Tolvanen , Aaron Tomlin Cc: linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Hao Ge , stable@vger.kernel.org Subject: [PATCH v4 2/2] alloc_tag: fix undetected compressed tag overflow when profiling is disabled Date: Mon, 10 Aug 2026 17:39:55 +0800 Message-Id: <20260810093955.153015-3-hao.ge@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260810093955.153015-1-hao.ge@linux.dev> References: <20260810093955.153015-1-hao.ge@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In reserve_module_tags(), the tag overflow check is gated on mem_alloc_profiling_enabled(): if (mem_alloc_profiling_enabled() && !tags_addressable()) If profiling is toggled off at runtime and a module is loaded whose tags exceed the compressed-mode limit, shutdown_mem_profiling() is skipped. vm_module_tags_populate() still maps memory for the tags and the module loads successfully, but the total tag count now exceeds what NR_UNUSED_PAGEFLAG_BITS can address. Once profiling is re-enabled, ref_to_idx() computes each tag's index as its position in the alloc_tag array. update_page_tag_ref() masks it to alloc_tag_ref_mask before storing in page->flags. Indices beyond the mask are truncated and idx_to_ref() resolves them to wrong tags. This silently corrupts /proc/allocinfo: allocated pages get attributed to the wrong call sites, so the statistics it reports are wrong. mem_alloc_profiling_enabled() and mem_profiling_compressed are independent. Once compressed mode is established at boot, it stays active regardless of runtime toggles of mem_profiling. Remove the mem_alloc_profiling_enabled() guard. On overflow, shut down profiling, release the reservation, and return -EAGAIN so that layout_and_allocate() retries with profiling disabled: codetag sections are then placed as regular module data and the module loads without profiling rather than being rejected entirely. Skip percpu counter allocation in load_module() when profiling is disabled, as those counters would never be freed on unload. Fixes: 4835f747d3ed ("alloc_tag: support for page allocation tag compression") Cc: stable@vger.kernel.org Suggested-by: Suren Baghdasaryan Signed-off-by: Hao Ge --- kernel/module/main.c | 17 +++++++++++++++-- mm/alloc_tag.c | 11 ++++++++--- 2 files changed, 23 insertions(+), 5 deletions(-) diff --git a/kernel/module/main.c b/kernel/module/main.c index 46dd8d25a605..c32bb47a573a 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -2971,13 +2971,26 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) * this is done generically; there doesn't appear to be any * special cases for the architectures. */ +retry: layout_sections(info->mod, info); layout_symtab(info->mod, info); /* Allocate and move to the final place */ err = move_module(info->mod, info); - if (err) - return ERR_PTR(err); + if (err) { + if (err != -EAGAIN) + return ERR_PTR(err); + /* + * -EAGAIN means profiling was disabled but the module + * can still load without it. Reset state and retry. + */ + rewrite_section_headers(info, flags); + for_each_mod_mem_type(type) + info->mod->mem[type].size = 0; + info->sechdrs[info->index.sym].sh_flags &= ~(unsigned long)SHF_ALLOC; + info->sechdrs[info->index.str].sh_flags &= ~(unsigned long)SHF_ALLOC; + goto retry; + } /* Module has been copied to its final place now: return it. */ mod = (void *)info->sechdrs[info->index.mod].sh_addr; diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c index af44f90379f2..3eba6331174d 100644 --- a/mm/alloc_tag.c +++ b/mm/alloc_tag.c @@ -950,10 +950,12 @@ static void *reserve_module_tags(struct module *mod, unsigned long size, int grow_res; module_tags.size = offset + size; - if (mem_alloc_profiling_enabled() && !tags_addressable()) { + if (!tags_addressable()) { shutdown_mem_profiling(true); - pr_warn("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n", - mod->name, NR_UNUSED_PAGEFLAG_BITS); + pr_warn_once("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n", + mod->name, NR_UNUSED_PAGEFLAG_BITS); + release_module_tags(mod, false); + return ERR_PTR(-EAGAIN); } grow_res = vm_module_tags_populate(); @@ -975,6 +977,9 @@ static int load_module(struct module *mod, struct codetag *start, struct codetag struct alloc_tag *stop_tag; struct alloc_tag *tag; + if (!mem_profiling_support) + return 0; + /* percpu counters for core allocations are already statically allocated */ if (!mod) return 0; -- 2.25.1