From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-196.mta0.migadu.com [91.218.175.196]) (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 EC68D373C00 for ; Wed, 30 Sep 2026 03:25:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.196 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790738756; cv=none; b=ZGXep7tT1mB1JCpRyWVcZp8igh+/Oihff5+ljWaAAKyXm+u2H06sUIyA/4UuIg/5WL46sc5ajxIxByjp72XJGF4oYFNPN7KaI6nZpcj10nr7l/YoVTYZdKZUhQoiIFhPYCnBksrcqlohoPGHZkh52L9KJ9Rqm/c7M3hBo6JALyo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790738756; c=relaxed/simple; bh=tmx3X4PgFtMsV+xxZ1IMDVsyAWoakSL8TqQSX2VjB/Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=P8EEFmCI6+8hb0x+SP4T8wubF7U/NmlxnJkcrrPQ1mn/kAKNfZfPmVzI9zdhjwBcqG4GI7JG5x6mSo1rVo1KucXmaNI61OMOxEVkpASQSTv9cfeSY+BmIgxFCfP9T9CvRg1ggjG4GjAnnBXbkqJfDidrdgz3l6+4w9FK/VdUHhw= 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=SLzA18dw; arc=none smtp.client-ip=91.218.175.196 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="SLzA18dw" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=tmx3X4PgFtMsV+xxZ1IMDVsyAWoakSL8TqQSX2VjB/Q=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790738751; v=1; x=1791343551; b=SLzA18dwU+mCXqj02LPTrThA3PD587eWehE2DOUGWvWMKJ8mgYvOEWdkz8S7ljxvzBXE5/Ie QtIcEKxpZPbnbDz6UUZeZf7ttLfTnqMIWQyHlHpDyFsI1nhOZfMf7aqFr+GCOGGqq7dBH7Iw/YR iPY0vF3+OdIfN0ykC5jyCUec= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 0e3241359faa91a0; Wed, 30 Sep 2026 03:25:51 +0000 X-Mizu-Trace-ID: 0e3241359faa91a0 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Wed, 30 Sep 2026 11:26:41 +0800 Precedence: bulk X-Mailing-List: linux-kernel@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 , Andrew Morton Cc: 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 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/ 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