From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-138.mta1.migadu.com [95.215.58.138]) (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 30DD54CE677 for ; Fri, 9 Oct 2026 11:29:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.138 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791545367; cv=none; b=hVIe3NeClRp0Hje9GtUQgwEeQxsafGxysY/YZu3NaUiYtg4DN3cMxszD7BVb9as4NsbCevV/uDbv25qpuI15T/YINvrul29IUYsX05SHj1tdbSH5lOWEQ1UVWfAbB4+Kft3CWG7VgJCuJ+04ipJBCpCymlRiJggha6VFZ/2wEcs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791545367; c=relaxed/simple; bh=9x2VgaCQqq1qe9Sd3mI+ji7pCRHxHu0WOqvf+sHVC10=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=nzrZor5MouatyJQ9eCH8dmkU2wTGR51aE7GZ9vnFQiH9taK8fM2ewfdP/yNeo+sVnzKy8vtD21oHRca/HqUipZ4LeISKJ/ZXlqQlK1GD7JnwDuVvd3J0TllCsXNdYmXsg14aAoHOb4r1gwwmrtjjTKqdSyddua4KudH1/DMLx7A= 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=oIAtzHD+; arc=none smtp.client-ip=95.215.58.138 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="oIAtzHD+" X-Envelope-To: linux-modules@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=9x2VgaCQqq1qe9Sd3mI+ji7pCRHxHu0WOqvf+sHVC10=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1791545353; v=1; x=1792150153; b=oIAtzHD+uyGDbZl2cSPP5H6EUsoC6yqhf1U++gKNvFIMGOyKEhJClrLnVuvCY793VrA007Y7 5eas06fDn2HdlS0g6su4jxWsW63kqxYajDnrDpvqWf1nPUNL8H5v6V5Vf43MWNRIQPhU9aYyojF tf6q36X2dohhfQoMuRkM9n0E= X-Envelope-To: linux-modules@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 13a9e522eed7582a; Fri, 09 Oct 2026 11:29:13 +0000 X-Mizu-Trace-ID: 13a9e522eed7582a X-Migadu-Flow: FLOW_OUT Message-ID: <839d13ef-8ca3-4e58-9bd0-84137f2d6866@linux.dev> Date: Fri, 9 Oct 2026 19:30:21 +0800 Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v11 0/7] alloc_tag and module codetag section fixes To: Suren Baghdasaryan Cc: Andrew Morton , Kent Overstreet , Luis Chamberlain , Petr Pavlu , Daniel Gomez , Sami Tolvanen , Aaron Tomlin , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Vlastimil Babka , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com References: <20260929082014.160587-1-hao.ge@linux.dev> <20260929134401.a1a385ff4369661f879b5d2f@linux-foundation.org> Content-Language: en-US From: Hao Ge In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Suren On 2026/10/5 02:37, Suren Baghdasaryan wrote: > On Wed, Sep 30, 2026 at 5:25 AM Hao Ge wrote: >> >> Hi Suren and Andrew >> >> >> On 2026/9/30 10:39, Suren Baghdasaryan wrote: >>> On Tue, Sep 29, 2026 at 8:44 PM Andrew Morton wrote: >>>> >>>> On Tue, 29 Sep 2026 16:20:07 +0800 Hao Ge wrote: >>>> >>>>> With profiling toggled off, the overflow check in >>>>> reserve_module_tags() did not run, a module could load with more >>>>> tags than the page flags can address, and re-enabling profiling >>>>> then silently corrupted /proc/allocinfo. On overflow the fix shuts >>>>> profiling down, releases the reservation and returns -EAGAIN, and >>>>> the codetag section lands as regular module data in the same load, >>>>> so the module loads without profiling. >>>>> >>>>> Review of the earlier series by Sashiko turned up more problems. >>>>> >>>>> One is a race. layout_sections() and move_module() both asked >>>>> codetag_needs_module_section() where a codetag section goes, and >>>>> mem_profiling_support can change between the two calls, for instance >>>>> when another module load overflows the tag index and shuts profiling >>>>> down. move_module() then copied the codetag section to offset 0 of >>>>> its regular destination and clobbered the first section placed in >>>>> that region. >>>>> >>>>> v7 reworks where codetag sections are allocated, on a prototype by >>>>> Petr Pavlu [1]. The allocation runs before layout_sections() and the >>>>> placement is decided in one step, so nothing re-asks the question >>>>> and the race is gone. The retry is gone too, on -EAGAIN the section >>>>> is laid out as regular module data right in the same load. >>>> >>>> Thanks. >>>> >>>> Seven patches, all cc:stable. Why is a backport proposed? >>>> Documentation/process/stable-kernel-rules.rst gives guidelines - does >>>> this series meet them? Does Suren have thoughts? >> >> Thanks, I've just gone through this carefully. >> >>> >>> I think vmalloc fix in patch#2 should be posted separately and clearly >>> quialifies for backporting as if fixes issues Hao found at [1]. >> >> Agreed. Patch #2 was added to this patch series because vm_module_tags_populate >> suffers from the same issue. If we want to be more conservative, I'd prefer to keep >> vm_module_tags_populate as it was in V10: >> https://lore.kernel.org/all/20260915070001.113559-3-hao.ge@linux.dev/ > > I disagree with this approach. That means we are introducing an extra > code inside vm_module_tags_populate() only to clean it up later. > Instead please post Patch #2 separately. That posting should have your > current patch that changes vmap_pages_xxx() to clean up on failure, > followed by patch(es) which remove unnecessary cleanup that some > functions currently perform by themselves. This patchset should > definitely be tagged for stable. You are right. Sorry for the confusion - my earlier deviation came from not fully understanding the rules for getting patches into the stable trees. > Once that patchset is accepted, the rest of your current patchset > fixing alloc_tags can be posted with correct assumption that > vmap_pages_range() cleans up its partial mapping when it fails. > > I know this sequence will take longer to upstream but I think it's the > right way to go. Make sense. Thanks for your continued support. Best Regards Hao > >> >> Then we can submit a fix for __GFP_NOFAIL retry loop in __vmalloc_area_node() as a hotfix together >> with our new patch #2. While at it, we can also check if there are any unnecessary calls to >> vunmap_range family functions that can be cleaned up now that patch #2 is applied. >> >> >>> >>> The rest are also bug fixes but their size is concerning. I'll review >>> them first before advising on which ones should be backported. Some >>> fixes address issues that happen very rarely and if a fix is too >>> complex it might make sense to leave it be or fix it some other way >>> with less churn. Please give me a couple of days to review them. With >>> the upcoming LPC I'm trying to multiplex between several projects. >> >> Thanks, sorry for all the hassle on you folks. >> >> Thanks >> Best Regards >> Hao >> >>> >>> [1] https://lore.kernel.org/all/b8005c24-ecac-45c4-840a-fd282f9693b5@linux.dev/ >>> >>>> >>>> Also, Sashiko has been busy again: >>>> https://sashiko.dev/#/patchset/20260929082014.160587-1-hao.ge@linux.dev