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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A559C49EA5 for ; Fri, 25 Jun 2021 02:40:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69E93613C0 for ; Fri, 25 Jun 2021 02:40:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232973AbhFYCmb (ORCPT ); Thu, 24 Jun 2021 22:42:31 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:8303 "EHLO szxga08-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232917AbhFYCmb (ORCPT ); Thu, 24 Jun 2021 22:42:31 -0400 Received: from dggeme703-chm.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4GB1LS1KQ3z1BRYp; Fri, 25 Jun 2021 10:34:56 +0800 (CST) Received: from [10.174.177.120] (10.174.177.120) by dggeme703-chm.china.huawei.com (10.1.199.99) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Fri, 25 Jun 2021 10:40:08 +0800 Subject: Re: [PATCH 1/3] mm: Add kvrealloc() To: Dave Chinner , , References: <20210625023029.1472466-1-david@fromorbit.com> <20210625023029.1472466-2-david@fromorbit.com> From: Miaohe Lin Message-ID: <867caabb-bac5-8b34-9a68-53e8953f2fad@huawei.com> Date: Fri, 25 Jun 2021 10:40:08 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210625023029.1472466-2-david@fromorbit.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.120] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggeme703-chm.china.huawei.com (10.1.199.99) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On 2021/6/25 10:30, Dave Chinner wrote: > From: Dave Chinner > > During log recovery of an XFS filesystem with 64kB directory > buffers, rebuilding a buffer split across two log records results > in a memory allocation warning from krealloc like this: > > xfs filesystem being mounted at /mnt/scratch supports timestamps until 2038 (0x7fffffff) > XFS (dm-0): Unmounting Filesystem > XFS (dm-0): Mounting V5 Filesystem > XFS (dm-0): Starting recovery (logdev: internal) > ------------[ cut here ]------------ > WARNING: CPU: 5 PID: 3435170 at mm/page_alloc.c:3539 get_page_from_freelist+0xdee/0xe40 > ..... > RIP: 0010:get_page_from_freelist+0xdee/0xe40 > Call Trace: > ? complete+0x3f/0x50 > __alloc_pages+0x16f/0x300 > alloc_pages+0x87/0x110 > kmalloc_order+0x2c/0x90 > kmalloc_order_trace+0x1d/0x90 > __kmalloc_track_caller+0x215/0x270 > ? xlog_recover_add_to_cont_trans+0x63/0x1f0 > krealloc+0x54/0xb0 > xlog_recover_add_to_cont_trans+0x63/0x1f0 > xlog_recovery_process_trans+0xc1/0xd0 > xlog_recover_process_ophdr+0x86/0x130 > xlog_recover_process_data+0x9f/0x160 > xlog_recover_process+0xa2/0x120 > xlog_do_recovery_pass+0x40b/0x7d0 > ? __irq_work_queue_local+0x4f/0x60 > ? irq_work_queue+0x3a/0x50 > xlog_do_log_recovery+0x70/0x150 > xlog_do_recover+0x38/0x1d0 > xlog_recover+0xd8/0x170 > xfs_log_mount+0x181/0x300 > xfs_mountfs+0x4a1/0x9b0 > xfs_fs_fill_super+0x3c0/0x7b0 > get_tree_bdev+0x171/0x270 > ? suffix_kstrtoint.constprop.0+0xf0/0xf0 > xfs_fs_get_tree+0x15/0x20 > vfs_get_tree+0x24/0xc0 > path_mount+0x2f5/0xaf0 > __x64_sys_mount+0x108/0x140 > do_syscall_64+0x3a/0x70 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Essentially, we are taking a multi-order allocation from kmem_alloc() > (which has an open coded no fail, no warn loop) and then > reallocating it out to 64kB using krealloc(__GFP_NOFAIL) and that is > then triggering the above warning. > > This is a regression caused by converting this code from an open > coded no fail/no warn reallocation loop to using __GFP_NOFAIL. > > What we actually need here is kvrealloc(), so that if contiguous > page allocation fails we fall back to vmalloc() and we don't > get nasty warnings happening in XFS. > > Fixes: 771915c4f688 ("xfs: remove kmem_realloc()") > Signed-off-by: Dave Chinner Thank you for your patch. > --- > fs/xfs/xfs_log_recover.c | 2 +- > include/linux/mm.h | 14 ++++++++++++++ > 2 files changed, 15 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c > index 1721fce2ec94..fee4fbadea0a 100644 > --- a/fs/xfs/xfs_log_recover.c > +++ b/fs/xfs/xfs_log_recover.c > @@ -2062,7 +2062,7 @@ xlog_recover_add_to_cont_trans( > old_ptr = item->ri_buf[item->ri_cnt-1].i_addr; > old_len = item->ri_buf[item->ri_cnt-1].i_len; > > - ptr = krealloc(old_ptr, len + old_len, GFP_KERNEL | __GFP_NOFAIL); > + ptr = kvrealloc(old_ptr, old_len, len + old_len, GFP_KERNEL); > memcpy(&ptr[old_len], dp, len); > item->ri_buf[item->ri_cnt-1].i_len += len; > item->ri_buf[item->ri_cnt-1].i_addr = ptr; > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 8ae31622deef..34d88ff00f31 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -830,6 +830,20 @@ static inline void *kvcalloc(size_t n, size_t size, gfp_t flags) > extern void kvfree(const void *addr); > extern void kvfree_sensitive(const void *addr, size_t len); > > +static inline void *kvrealloc(void *p, size_t oldsize, size_t newsize, > + gfp_t flags) > +{ > + void *newp; > + > + if (oldsize >= newsize) > + return p; > + newp = kvmalloc(newsize, flags); Shouldn't we check newp against NULL before memcpy? Thanks. > + memcpy(newp, p, oldsize); > + kvfree(p); > + return newp; > +} > + > + > static inline int head_compound_mapcount(struct page *head) > { > return atomic_read(compound_mapcount_ptr(head)) + 1; >