From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f71.google.com (mail-oi0-f71.google.com [209.85.218.71]) by kanga.kvack.org (Postfix) with ESMTP id 7D6936B0006 for ; Fri, 16 Mar 2018 09:14:35 -0400 (EDT) Received: by mail-oi0-f71.google.com with SMTP id d142so5107293oih.4 for ; Fri, 16 Mar 2018 06:14:35 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [202.181.97.72]) by mx.google.com with ESMTPS id q84si1936515oia.184.2018.03.16.06.14.32 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 16 Mar 2018 06:14:33 -0700 (PDT) Subject: Re: [PATCH] mm/shmem: Do not wait for lock_page() in shmem_unused_huge_shrink() From: Tetsuo Handa References: <20180316105908.62516-1-kirill.shutemov@linux.intel.com> <20180316121303.GI23100@dhcp22.suse.cz> <20180316122508.fv4edpx34hdqybwx@node.shutemov.name> <20180316125827.GC11461@dhcp22.suse.cz> <20180316130200.rbke66zjyoc6zwzl@node.shutemov.name> In-Reply-To: <20180316130200.rbke66zjyoc6zwzl@node.shutemov.name> Message-Id: <201803162214.ECJ30715.StOOFHOFVLJMQF@I-love.SAKURA.ne.jp> Date: Fri, 16 Mar 2018 22:14:24 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: kirill@shutemov.name, mhocko@kernel.org Cc: kirill.shutemov@linux.intel.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux-mm@lists.ewheeler.net f2fs is doing page = f2fs_pagecache_get_page(inode->i_mapping, 0, FGP_LOCK|FGP_NOWAIT, 0); which calls struct page *pagecache_get_page(inode->i_mapping, 0, FGP_LOCK|FGP_NOWAIT, 0); . Then, can't we define static inline struct page *find_trylock_page(struct address_space *mapping, pgoff_t offset) { return pagecache_get_page(mapping, offset, FGP_LOCK|FGP_NOWAIT, 0); } and replace find_lock_page() with find_trylock_page() ? Also, won't ---------- diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 34ce3ebf..0cfc329 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -479,6 +479,8 @@ static inline int trylock_page(struct page *page) static inline void lock_page(struct page *page) { might_sleep(); + WARN_ONCE(current->flags & PF_MEMALLOC, + "lock_page() from reclaim context might deadlock"); if (!trylock_page(page)) __lock_page(page); } @@ -491,6 +493,8 @@ static inline void lock_page(struct page *page) static inline int lock_page_killable(struct page *page) { might_sleep(); + WARN_ONCE(current->flags & PF_MEMALLOC, + "lock_page_killable() from reclaim context might deadlock"); if (!trylock_page(page)) return __lock_page_killable(page); return 0; ---------- help find lock_page() users in deep reclaim paths? ---------- [ 100.314083] ------------[ cut here ]------------ [ 100.315695] lock_page() from reclaim context might deadlock [ 100.315708] WARNING: CPU: 1 PID: 56 at ./include/linux/pagemap.h:483 pagecache_get_page+0x245/0x250 [ 100.319686] Modules linked in: sg pcspkr i2c_piix4 vmw_vmci shpchp sd_mod ata_generic pata_acpi serio_raw vmwgfx drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ahci mptspi libahci scsi_transport_spi mptscsih ata_piix mptbase i2c_core e1000 libata ipv6 [ 100.325951] CPU: 1 PID: 56 Comm: kswapd0 Kdump: loaded Not tainted 4.16.0-rc5-next-20180315+ #696 [ 100.328439] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017 [ 100.331625] RIP: 0010:pagecache_get_page+0x245/0x250 [ 100.333211] RSP: 0018:ffffc9000085bc00 EFLAGS: 00010286 [ 100.334832] RAX: 0000000000000000 RBX: ffffea0004ad3100 RCX: 0000000000000007 [ 100.336900] RDX: 0000000000000b63 RSI: ffff88013aa0b700 RDI: ffff88013aa0ae80 [ 100.339068] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 [ 100.341108] R10: 0000000000000040 R11: 0000000000000000 R12: ffff880139b6e0c8 [ 100.343153] R13: 0000000000000000 R14: ffffffff82068220 R15: 0000000000000002 [ 100.345242] FS: 0000000000000000(0000) GS:ffff88013bc40000(0000) knlGS:0000000000000000 [ 100.347510] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 100.349277] CR2: 00007f326c67e000 CR3: 000000000200f006 CR4: 00000000001606e0 [ 100.351343] Call Trace: [ 100.352374] ? iput+0x52/0x2f0 [ 100.353567] shmem_unused_huge_shrink+0x2e9/0x380 [ 100.355112] super_cache_scan+0x17a/0x180 [ 100.356553] shrink_slab+0x218/0x590 [ 100.357854] shrink_node+0x346/0x350 [ 100.359161] kswapd+0x322/0x930 [ 100.360370] kthread+0xf0/0x130 [ 100.361566] ? mem_cgroup_shrink_node+0x320/0x320 [ 100.363112] ? kthread_create_on_node+0x60/0x60 [ 100.364634] ret_from_fork+0x3a/0x50 [ 100.365943] Code: db e8 70 4c 01 00 e9 5e fe ff ff 80 3d 44 51 f8 00 00 0f 85 46 ff ff ff 48 c7 c7 60 11 df 81 c6 05 30 51 f8 00 01 e8 5b 86 ee ff <0f> 0b e9 2c ff ff ff 0f 1f 40 00 83 e2 02 53 8b 8f 48 01 00 00 [ 100.371197] ---[ end trace b50eee6f891efec3 ]--- ----------