From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 06AD43921DD; Wed, 12 Aug 2026 05:41:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786513271; cv=none; b=KJUVtLwqZ6qwuF+aX3gteKVJzfzOuGto6mIsrSBil+dz8H2gyTdTo6zq8iTu9lIi0+I97m8d7wk5l/L7+So/V7+RAlxqZhmdoo+mS79E0VsgRfwscMAR7mdS2ZIjEyVJqCZfY8vmQR+1SKsEWveyvJlefZ2EIm8lQq70AH3adqA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786513271; c=relaxed/simple; bh=E6uGsbGqqzCkRoxACNAXopQ2UoUWKRxtKe6zwPPJj0w=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=K1Ivu3bRjuY+RB+ZXeIcZx1i3Yw2t1MzgKkz+pWova9y1wk4fXSM6UbD+6BQ4rs7HbSIHP0lYHPoezveprVADRbWLcJqNmZqLefHtdQgsC/6JOsfXatMNtzVsO3ySj+XVFAlXEPLehmK61RD0oEcJYuERrJaczU8wwmlrf2Ze/U= 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=Whpnxh9p; arc=none smtp.client-ip=95.215.58.188 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="Whpnxh9p" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1786513266; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TJw8Kb7KYo62APlX8MEZxvAZlhH4o0ziACenqfJhSwk=; b=Whpnxh9pXp2+bTxNYX9GyGV2YNWyFmEhiFLBxTHM1emfN+vJjElCcTotxQwVy3X1umLo6t yiTOJm0OqPnobb7aV185QEy//Yh3hnbhvUFaABU9uMRD6FwBkggx2YIhowltCfc/AyM1lq HTTnFTnQdY/3c7KPSiV2czkyKaweldU= 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 v5 2/2] alloc_tag: fix undetected compressed tag overflow when profiling is disabled Date: Wed, 12 Aug 2026 13:41:05 +0800 Message-Id: <20260812054105.102637-3-hao.ge@linux.dev> In-Reply-To: <20260812054105.102637-1-hao.ge@linux.dev> References: <20260812054105.102637-1-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 X-Migadu-Flow: FLOW_OUT 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. 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 | 25 +++++++++++++++++++++++-- mm/alloc_tag.c | 8 +++++--- 2 files changed, 28 insertions(+), 5 deletions(-) diff --git a/kernel/module/main.c b/kernel/module/main.c index 46dd8d25a605..ed26f167be84 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -2944,6 +2944,7 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) { struct module *mod; int err; + unsigned long frob_size[MOD_MEM_NUM_TYPES]; /* Allow arches to frob section contents and sizes. */ err = module_frob_arch_sections(info->hdr, info->sechdrs, @@ -2966,18 +2967,38 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) */ module_mark_ro_after_init(info->hdr, info->sechdrs, info->secstrings); + /* + * Save the sizes reserved by module_frob_arch_sections() so they can + * be restored if we retry below. + */ + for_each_mod_mem_type(type) + frob_size[type] = info->mod->mem[type].size; + /* * Determine total sizes, and put offsets in sh_entsize. For now * 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 = frob_size[type]; + 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..0a7b657fe2de 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(); -- 2.25.1