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Wed, 21 Jan 2026 16:15:55 +0800 (CST) Received: from kwepemr500001.china.huawei.com (unknown [7.202.194.229]) by mail.maildlp.com (Postfix) with ESMTPS id 2AE58405A8; Wed, 21 Jan 2026 16:19:58 +0800 (CST) Received: from [10.174.179.179] (10.174.179.179) by kwepemr500001.china.huawei.com (7.202.194.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 21 Jan 2026 16:19:57 +0800 Message-ID: Date: Wed, 21 Jan 2026 16:19:56 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] mm/khugepaged: free empty xa_nodes when rollbacks in collapse_file To: Matthew Wilcox CC: , , , , , , , , , , , , , , References: <20260121062243.1893129-1-tujinjiang@huawei.com> From: Jinjiang Tu In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.179] X-ClientProxiedBy: kwepems100002.china.huawei.com (7.221.188.206) To kwepemr500001.china.huawei.com (7.202.194.229) X-Rspam-User: X-Rspamd-Queue-Id: 64C9D100003 X-Rspamd-Server: rspam12 X-Stat-Signature: gkz73a9aop4c9wtc6i44bkhqbj7dun7c X-HE-Tag: 1768983603-594214 X-HE-Meta: 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 lc3hUIpc 8hfKxAqF7PpRFWjuB9x5LqV4RvaizYODJB6CPmn2SIJIO/eDTk2qvuUpStxY6JdWIdIO1S4OvJWQ7jcyAv/dmHtb2x3IDc92020ORTHkHFoR4id2El/CrZVyXJJqzP9r5wHffkenOpdwwzvMLnVxd4fh23gVsMXwgi4qhv6aLAfX6uB6ZV8DzVpUXAxmwfUVpFmRqa9OyL/DnEpXhwfStuLRYHZ+Oi+HqbY1ueCVNegIVvS6AXI/LSJS+VjrDk7zNE3omYFZgbozpJPiz5WiX45UT+tid4OlYKknRI7sh2XWUZmL0Gq0sUvnX0XylMvnqQe5ktlhQPRxbcaf812cFUw1PGOagVu7yx6JRr+QG2ZZ+4FoE0seKW47h98Ow4vv/JE+j 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: 在 2026/1/21 14:38, Matthew Wilcox 写道: > On Wed, Jan 21, 2026 at 02:22:43PM +0800, Jinjiang Tu wrote: >> collapse_file() calls xas_create_range() to pre-create all slots needed. >> If collapse_file() finally fails, these pre-created slots are empty nodes >> and aren't destroyed. > try this instead > > diff --git a/fs/inode.c b/fs/inode.c > index cff1d3af0d57..85886af1e7ab 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -744,22 +744,18 @@ void dump_mapping(const struct address_space *mapping) > > void clear_inode(struct inode *inode) > { > - /* > - * We have to cycle the i_pages lock here because reclaim can be in the > - * process of removing the last page (in __filemap_remove_folio()) > - * and we must not free the mapping under it. > - */ > - xa_lock_irq(&inode->i_data.i_pages); > - BUG_ON(inode->i_data.nrpages); > /* > * Almost always, mapping_empty(&inode->i_data) here; but there are > * two known and long-standing ways in which nodes may get left behind > * (when deep radix-tree node allocation failed partway; or when THP > - * collapse_file() failed). Until those two known cases are cleaned up, > - * or a cleanup function is called here, do not BUG_ON(!mapping_empty), > - * nor even WARN_ON(!mapping_empty). > + * collapse_file() failed). > + * > + * xa_destroy() also cycles the lock for us, which is needed because > + * reclaim can be in the process of removing the last folio (in > + * __filemap_remove_folio()) and we must not free the mapping under it. > */ > - xa_unlock_irq(&inode->i_data.i_pages); > + xa_destroy(&inode->i_data.i_pages); > + BUG_ON(inode->i_data.nrpages); > BUG_ON(!list_empty(&inode->i_data.i_private_list)); > BUG_ON(!(inode->i_state & I_FREEING)); > BUG_ON(inode->i_state & I_CLEAR); I tried it, and the memleak disappears.