From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-87.mta1.migadu.com [95.215.58.87]) (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 A78093C8728 for ; Thu, 13 Aug 2026 09:34:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.87 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786613657; cv=none; b=g65kEF9cK/w01m9jGBb3UTDZoYXku8MNk37OiQds4e7eEdPMk0UNj92x4lTmmfqpd52Q46XxMUqFsXDnZmh0FnPdF1BkeG9UDbaTBvWLCCjEmzy3ilo1q/PsTEHUCI5d4I+kSvWe3mcmxJ+7ssl0iRM4+Q3C56llxrKYJlYODWM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786613657; c=relaxed/simple; bh=p4TFMUd9q6GnbcN5ey2myrD4Zw8jApQ5r7UvSVGLQQM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=GBfXxI1iKNuPCopcLP4rNeWzfSVLh51rTJP82bN3iH5aW0cuyuaOQf1dHkLC4tL3dUw5+MoVyhkpU84EHLiIzixwHs5M083ExOMnei1zL+ygcx+h96I7xMThAvI03aKbIieHZyeh6NTAxC3r1lA//EAz7N+9DhKU0xu0ORTxSck= 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=ZxW9+DB6; arc=none smtp.client-ip=95.215.58.87 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="ZxW9+DB6" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=p4TFMUd9q6GnbcN5ey2myrD4Zw8jApQ5r7UvSVGLQQM=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786613651; v=1; x=1787218451; b=ZxW9+DB6bwXRqzZq8to0yNNVzyfWCIMwxMxlc5JgvV4rHQ3KWecsC7XHr0G4Xeh/h48qWaS2 qhMBoC3VqyRvFWWskbpQ4+TzVE/tiN2FlUJkrm8zTkkI6Vb7gX65e7MM9s7C2+TSjmfuYNBgg2X HP2JVkv+W56xc2ybPj/dKZDU= X-Envelope-To: linux-kernel@vger.kernel.org Received: from localhost.localdomain (116.128.244.169) by smtp.migadu.com with ESMTPS id f70264e86958a884; Thu, 13 Aug 2026 09:34:11 +0000 X-Migadu-Flow: FLOW_OUT 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 Subject: [RFC PATCH 2/3] module: move codetag section placement decision to layout_sections() Date: Thu, 13 Aug 2026 17:34:20 +0800 Message-Id: <20260813093421.135230-3-hao.ge@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260813093421.135230-1-hao.ge@linux.dev> References: <20260813093421.135230-1-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 codetag_needs_module_section() is called twice per codetag section, once in layout_sections() and once in move_module(), and both depend on mem_profiling_support, which changes without a lock. If profiling is disabled between the two calls, layout excludes the section (offset 0) while move copies it as normal memory to offset 0: CPU0 (insmod A) CPU1 (insmod B) ---------------- ---------------- layout_sections() needs_section_mem() == true sh_entsize: type, offset = 0 reserve_module_tags() overflows shutdown_mem_profiling() mem_profiling_support = false move_module() needs_section_mem() == false offset = sh_entsize & MASK = 0 memcpy(mod->mem[type].base + 0, ...) -> overwrites the first section there Record the decision in layout_sections() in sh_entsize using a MOD_MEM_CODETAG type, and have move_module() use that instead of asking again. reserve_module_tags() returns -EAGAIN if profiling was disabled after layout, so the loader retries and places the section as normal memory. Fixes: 4835f747d3ed ("alloc_tag: support for page allocation tag compression") Signed-off-by: Hao Ge --- include/linux/module.h | 11 +++++++++++ kernel/module/main.c | 17 ++++++----------- mm/alloc_tag.c | 8 ++++++++ 3 files changed, 25 insertions(+), 11 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 7566815fabbe..a02016528e1d 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -328,6 +328,17 @@ enum mod_mem_type { MOD_INVALID = -1, }; +/* + * If CONFIG_CODE_TAGGING is on, modules get a .codetag section. + * codetag_needs_module_section() says where it goes: the usual + * mod->mem[], or off to the codetag region. + * + * Mark the codetag-region ones with MOD_MEM_NUM_TYPES. + * It's just past the real types, so it doesn't index into mod->mem[] + * and for_each_mod_mem_type() skips it. + */ +#define MOD_MEM_CODETAG MOD_MEM_NUM_TYPES + #define mod_mem_type_is_init(type) \ ((type) == MOD_INIT_TEXT || \ (type) == MOD_INIT_DATA || \ diff --git a/kernel/module/main.c b/kernel/module/main.c index ed26f167be84..2337bf604f58 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -1728,11 +1728,8 @@ static void __layout_sections(struct module *mod, struct load_info *info, bool i * preallocated contiguous memory. */ if (codetag_needs_module_section(mod, sname, s->sh_size)) { - /* - * s->sh_entsize won't be used but populate the - * type field to avoid confusion. - */ - s->sh_entsize = ((unsigned long)(type) & SH_ENTSIZE_TYPE_MASK) + s->sh_entsize = ((unsigned long)MOD_MEM_CODETAG + & SH_ENTSIZE_TYPE_MASK) << SH_ENTSIZE_TYPE_SHIFT; continue; } @@ -2815,11 +2812,10 @@ static int move_module(struct module *mod, struct load_info *info) continue; sname = info->secstrings + shdr->sh_name; - /* - * Load codetag sections separately as they might still be used - * after module unload. - */ - if (codetag_needs_module_section(mod, sname, shdr->sh_size)) { + + enum mod_mem_type type = shdr->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT; + + if (type == MOD_MEM_CODETAG) { dest = codetag_alloc_module_section(mod, sname, shdr->sh_size, arch_mod_section_prepend(mod, i), shdr->sh_addralign); if (WARN_ON(!dest)) { @@ -2832,7 +2828,6 @@ static int move_module(struct module *mod, struct load_info *info) } codetag_section_found = true; } else { - enum mod_mem_type type = shdr->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT; unsigned long offset = shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK; dest = mod->mem[type].base + offset; diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c index 461fa87fbb0b..7481180dadd2 100644 --- a/mm/alloc_tag.c +++ b/mm/alloc_tag.c @@ -893,6 +893,14 @@ static void *reserve_module_tags(struct module *mod, unsigned long size, if (size < sizeof(struct alloc_tag)) return ERR_PTR(-EINVAL); + /* + * Profiling may have been disabled by a concurrent module load. + * Return -EAGAIN so the loader retries with profiling off, laying + * the section out as ordinary module memory. + */ + if (!mem_profiling_support) + return ERR_PTR(-EAGAIN); + /* * align is always power of 2, so we can use IS_ALIGNED and ALIGN. * align 0 or 1 means no alignment, to simplify set to 1. -- 2.25.1