From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 11E75CEFCF0 for ; Tue, 6 Jan 2026 18:55:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 79FB46B0088; Tue, 6 Jan 2026 13:55:40 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 76D316B008A; Tue, 6 Jan 2026 13:55:40 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 64BA96B0092; Tue, 6 Jan 2026 13:55:40 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 545986B0088 for ; Tue, 6 Jan 2026 13:55:40 -0500 (EST) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id DA43B1407E9 for ; Tue, 6 Jan 2026 18:55:39 +0000 (UTC) X-FDA: 84302442798.03.22328DF Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf08.hostedemail.com (Postfix) with ESMTP id 1E929160008 for ; Tue, 6 Jan 2026 18:55:37 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=USbYp16l; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf08.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1767725738; a=rsa-sha256; cv=none; b=VN5rzvcUWlsCtINRLIfRDeZoB7uiB/ChMJObR6talgfIRUPfYfsVeSTuzRyu7KDI3ZahwB 3rVRx4bRqDMZ+sQZ+0TAaBZ2ITJpMAX3FZiWQtarITCA/rFcaTalnUGzImTCeOFAJSr1gA rskFOn0qemozgfo5r8GT+FSCM62zOdY= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=USbYp16l; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf08.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1767725738; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Cgc/MRC2Kt/tylO8oRaEYCBG9AfDbKFCC5xErnQMX6E=; b=P8y2gqA8yVyHpVBPibhmLYXZEFlXOi3FXIgxSS9AwMUmr5BxcFmHvweVbOTROfDiuQLC6v l9OmeQLLhju19IMY2hzd0ZUUH3hZH48g/gwmed8RtUTZW04acwx9PWCt83yLoPLeJ3hk4F /TXZH9n0c5416mxuG4Nx/w+CXGD+muA= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 4CD2260007; Tue, 6 Jan 2026 18:55:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F119C116C6; Tue, 6 Jan 2026 18:55:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767725737; bh=l79MN7k7m7NEtZrL6dffvPEx0BF2/cRLOCmREMCGAsE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=USbYp16lLYrltyJvcP4H6/5miQe/JsVg+JK/ckh4Y7nMkM7bXWBJQCjg+7X6pCvjY vZ+IbRdDhXsNpSGmIfbRDX2J7C30nMpLrZUOybTUBWwi66kE/F6iXWeAuwDCOTpf0w wmyjJ72zd1l7CfrR8kd/nbmhHue9BdX/0BOZjyAilN8S9uvLGfbyDkxH1UDr/C/f7L 4ih5zK2fuLFlo2va1/TuPAjk6tc+dtPOcA5rnoE+VtfSlE7K/+5LFLymzcyZtB824P RiMuSBBC0Qv4ZxRfOBF4FlbB/0ENUMV3QKJwDkqQkj/8j2ZkaRgJoLMZNcbD0KGwwn BKVhf5gtS/1fw== Message-ID: Date: Tue, 6 Jan 2026 19:55:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [bug report] memory leak of xa_node in collapse_file() when rollbacks To: Jinjiang Tu , Shardul Bankar , Andrew Morton , Matthew Wilcox , ziy@nvidia.com, lorenzo.stoakes@oracle.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Cc: Kefeng Wang , shardulsb08@gmail.com References: <86834731-02ba-43ea-9def-8b8ca156ec4a@huawei.com> <32e4658f-d23b-4bae-9053-acdd5277bb17@kernel.org> <4b129453-97d1-4da4-9472-21c1634032d0@huawei.com> <05bbe26e-e71a-4a49-95d2-47373b828145@kernel.org> <308b7b3c4f6c74c46906e25d6069049c70222ed8.camel@mpiricsoftware.com> <43024ae3-4131-4381-a766-5ca674d3f87d@huawei.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAa2VybmVsLm9yZz7CwY0EEwEIADcWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCaKYhwAIbAwUJJlgIpAILCQQVCgkIAhYCAh4FAheAAAoJEE3eEPcA/4Naa5EP/3a1 9sgS9m7oiR0uenlj+C6kkIKlpWKRfGH/WvtFaHr/y06TKnWn6cMOZzJQ+8S39GOteyCCGADh 6ceBx1KPf6/AvMktnGETDTqZ0N9roR4/aEPSMt8kHu/GKR3gtPwzfosX2NgqXNmA7ErU4puf zica1DAmTvx44LOYjvBV24JQG99bZ5Bm2gTDjGXV15/X159CpS6Tc2e3KvYfnfRvezD+alhF XIym8OvvGMeo97BCHpX88pHVIfBg2g2JogR6f0PAJtHGYz6M/9YMxyUShJfo0Df1SOMAbU1Q Op0Ij4PlFCC64rovjH38ly0xfRZH37DZs6kP0jOj4QdExdaXcTILKJFIB3wWXWsqLbtJVgjR YhOrPokd6mDA3gAque7481KkpKM4JraOEELg8pF6eRb3KcAwPRekvf/nYVIbOVyT9lXD5mJn IZUY0LwZsFN0YhGhQJ8xronZy0A59faGBMuVnVb3oy2S0fO1y/r53IeUDTF1wCYF+fM5zo14 5L8mE1GsDJ7FNLj5eSDu/qdZIKqzfY0/l0SAUAAt5yYYejKuii4kfTyLDF/j4LyYZD1QzxLC MjQl36IEcmDTMznLf0/JvCHlxTYZsF0OjWWj1ATRMk41/Q+PX07XQlRCRcE13a8neEz3F6we 08oWh2DnC4AXKbP+kuD9ZP6+5+x1H1zEzsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCgh Cj/CA/lc/LMthqQ773gauB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseB fDXHA6m4B3mUTWo13nid0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts 6TZ+IrPOwT1hfB4WNC+X2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiu Qmt3yqrmN63V9wzaPhC+xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKB Tccu2AXJXWAE1Xjh6GOC8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvF FFyAS0Nk1q/7EChPcbRbhJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh 2YmnmLRTro6eZ/qYwWkCu8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRk F3TwgucpyPtcpmQtTkWSgDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0L LH63+BrrHasfJzxKXzqgrW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4v q7oFCPsOgwARAQABwsF8BBgBCAAmAhsMFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAmic2qsF CSZYCKEACgkQTd4Q9wD/g1oq0xAAsAnw/OmsERdtdwRfAMpC74/++2wh9RvVQ0x8xXvoGJwZ rk0Jmck1ABIM//5sWDo7eDHk1uEcc95pbP9XGU6ZgeiQeh06+0vRYILwDk8Q/y06TrTb1n4n 7FRwyskKU1UWnNW86lvWUJuGPABXjrkfL41RJttSJHF3M1C0u2BnM5VnDuPFQKzhRRktBMK4 GkWBvXlsHFhn8Ev0xvPE/G99RAg9ufNAxyq2lSzbUIwrY918KHlziBKwNyLoPn9kgHD3hRBa Yakz87WKUZd17ZnPMZiXriCWZxwPx7zs6cSAqcfcVucmdPiIlyG1K/HIk2LX63T6oO2Libzz 7/0i4+oIpvpK2X6zZ2cu0k2uNcEYm2xAb+xGmqwnPnHX/ac8lJEyzH3lh+pt2slI4VcPNnz+ vzYeBAS1S+VJc1pcJr3l7PRSQ4bv5sObZvezRdqEFB4tUIfSbDdEBCCvvEMBgoisDB8ceYxO cFAM8nBWrEmNU2vvIGJzjJ/NVYYIY0TgOc5bS9wh6jKHL2+chrfDW5neLJjY2x3snF8q7U9G EIbBfNHDlOV8SyhEjtX0DyKxQKioTYPOHcW9gdV5fhSz5tEv+ipqt4kIgWqBgzK8ePtDTqRM qZq457g1/SXSoSQi4jN+gsneqvlTJdzaEu1bJP0iv6ViVf15+qHuY5iojCz8fa0= In-Reply-To: <43024ae3-4131-4381-a766-5ca674d3f87d@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 1E929160008 X-Rspamd-Server: rspam10 X-Stat-Signature: xktdx6dtmgt6ia5q43qn4t89m1c1bccb X-HE-Tag: 1767725737-804888 X-HE-Meta: U2FsdGVkX1/OzDRPyp8/t1RhbJk5wbYSTbM8wYEwE6xe2YTN8V9xbI+UDJ931rzfKp0FLpJHy6C3NSZ0kTWPPgwhzJkgv/0OGQ5Hp6GpDJ18H65n35EL5RPNncmxBS7EswtduG6ndYB/IMXfM8GT7kXzEz9m+NbWoOgGLy1MzzKGRx4e4J0Jca4NrrGp0CodSuVOPeLsoefzSH7mzu7kYoyVs0Yk6yshkNDNuWYih2yadXRYA2i2AHLzZOTbkPesIMwlSvo5v6/jQsz8olLXce3Vk4tHhjCDmkko3a5NfhZ+wiJ1+0XLKGNJ4fB5Rs3tOjWtedrx/lB3s+3UVvHmslbZST0C5F8jkHixRGpJ3z+PPLRzhPpPA4HceaumX55iQQsr43L3ym5JxtoYoMvQkAa8w4KNSsMY5I0f+31g0zneyFdQBZGHKNKf/yVNhRDQgNA6ucrfG/aq7A1PAOYOaoyZCvddidonKQ5KV8ip/3A5p3mNoeIKnXy/vPhbxzdPDQPDZvJthMj6gOEtL/fc0SYyM/QAFcFPRIaj7mVIuogvT/tzZgp27D0aK1GO6jySKU3v5NsJX2V97qgY1oigUnCobcKNY1rIVYnlQ+DC0i1k6caSvkOF3Yip8iCzgkuTIrAi4waZ4+CjrOGQsdCgWAlWJkgRkubiFXJsXLPkzg4zdxtq7SM4Vmjb3z7vDL08fhpKsgWIMkmhnpKQrcuqT3pZigEnVAydaQWaBlEd8PUFi8ktjOQy3S2S/M9SqMSwrXF+onsseQGNs/Bg+IPOzsWQg1LiAwUD+uZnsAhyN9WA4CHWApYcwsblj41I0DsWv5++nni+gK4+dAeXAru942EDBKeHx/H2zfRMd0oPDQ+0SuxEB+oTDw+fyHqrU6kCvX+sE5HhUHFa6BpG5kDlZd5503JMuh5a1PBv15pqmmtZcfEgzHY0gLuFMEYjdxzNZl/LVixD82NXexh97JK LlWvZ345 2HHXLLCdlboitcp1LenvS1MvXQ19f6X4ZiPV2UiJbn7ZSEn7MQw7BxKjrcOacyZe3AEnhpvnUGOrP0y2noKuNuPFMYYrj6C1CSUfNvBd0m2xPuYSwjWyiIT9L9WxAaSya5Yy5hI9tUEW2iR0Mz3/WXMYkCxzgN+BMnCi9dd1rj4rnu7ajASYuaJIUs764eI97V2j7fPA7l1LJR3NpAhPCeWTY+szHq2KAxSrGFZloip5YnYyc98+oZPuLVYb4v2+OBwfwsrtRxLiFIkgdB0eDCBIb68dokf7um1QIPZM1WKNg8dRbNvJs0/sKiXHFXf8/vSteb2DgSAmn3nY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 12/31/25 07:29, Jinjiang Tu wrote: > > 在 2025/12/31 5:03, David Hildenbrand (Red Hat) 写道: >> On 12/27/25 02:24, Jinjiang Tu wrote: >>> >>> 在 2025/12/25 12:15, Shardul Bankar 写道: >>>> On Thu, 2025-12-18 at 21:11 +0800, Jinjiang Tu wrote: >>>>> 在 2025/12/18 20:49, David Hildenbrand (Red Hat) 写道: >>>>>>    Thanks for checking. I thought that was also discussed as part of >>>>>> the other fix. >>>>>>       See [2] where we have >>>>>>       "Note: This fixes the leak of pre-allocated nodes. A >>>>>> separate fix >>>>>> will >>>>>>    be needed to clean up empty nodes that were inserted into the tree >>>>>> by >>>>>>    xas_create_range() but never populated." >>>>>>       Is that the issue you are describing? (sounds like it, but I >>>>>> only >>>>>> skimmed over the details). >>>>>>       CCing Shardul. >>>>> Yes, the same issue. As I descirbed in the first email: >>>>> " >>>>> At first, I tried to destory the empty nodes when collapse_file() >>>>> goes to rollback path. However, >>>>> collapse_file() only holds xarray lock and may release the lock, so >>>>> we couldn't prevent concurrent >>>>> call of collapse_file(), so the deleted empty nodes may be needed by >>>>> other collapse_file() calls. >>>>> " >>>> Hi David, Jinjiang, >>>> >>>> As Jinjiang mentioned, this appears to address what I had originally >>>> referred to in the "Note:" in [1]. >>>> >>>> Just to clarify the context of the "Note:", that was based on my >>>> assumption at the time that such empty nodes would be considered leaks. >>>> After Dev’s feedback in [2]: >>>> "No "fix" is needed in this case, the empty nodes are there in the tree >>>> and there is no leak." >>>> >>>> and looking at the older discussion in [3]: >>>> "There's nothing to free; if a node is allocated, then it's stored in >>>> the tree where it can later be found and reused. " >>> >>> However, if the empty nodes aren't reused, When the file is deleted, >>> shmem_evict_inode()->shmem_truncate_range() traverses all entries and >>> calls xas_store(xas, NULL) to delete, if the leaf xa_node that stores >>> deleted entry becomes empty, xas_store() will automatically delete the >>> empty node and delete it's parent is empty too, until parent node isn't >>> empty. shmem_evict_inode() won't traverse the empty nodes created by >>> xas_create_range() due to these nodes doesn't store any entries. >> >> So you're saying that nothing/nobody would clean up these xarray >> entries and we'd be leaking them? > Yes. >> >> "struct xarray" documents "If all of the entries in the array are >> NULL, @xa_head is a NULL pointer.". So we depend on all entries being >> set to NULL in order to properly cleanup/free the xarray automatically. >> > Yes Okay, then we really have to tackle this. Any takers? :) -- Cheers David