From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751722AbdHGOJu (ORCPT ); Mon, 7 Aug 2017 10:09:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36176 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750751AbdHGOJs (ORCPT ); Mon, 7 Aug 2017 10:09:48 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com A60737D0FB Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=asavkov@redhat.com Date: Mon, 7 Aug 2017 16:09:47 +0200 From: Artem Savkov To: Thomas Gleixner Cc: "Paul E. McKenney" , linux-kernel@vger.kernel.org Subject: possible circular locking dependency mmap_sem/cpu_hotplug_lock.rw_sem Message-ID: <20170807140947.nhfz2gel6wytl6ia@shodan.usersys.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline User-Agent: NeoMutt/20161126 (1.7.1) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 07 Aug 2017 14:09:48 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, After commit fc8dffd "cpu/hotplug: Convert hotplug locking to percpu rwsem" the following lockdep splat started showing up on some systems while running ltp's madvise06 test (right after first dirty_pages call [1]). [1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/madvise/madvise06.c#L136 [21002.630252] ====================================================== [21002.637148] WARNING: possible circular locking dependency detected [21002.644045] 4.13.0-rc3-next-20170807 #12 Not tainted [21002.649583] ------------------------------------------------------ [21002.656492] a.out/4771 is trying to acquire lock: [21002.661742] (cpu_hotplug_lock.rw_sem){++++++}, at: [] drain_all_stock.part.35+0x18/0x140 [21002.672629] [21002.672629] but task is already holding lock: [21002.679137] (&mm->mmap_sem){++++++}, at: [] __do_page_fault+0x175/0x530 [21002.688371] [21002.688371] which lock already depends on the new lock. [21002.688371] [21002.697505] [21002.697505] the existing dependency chain (in reverse order) is: [21002.705856] [21002.705856] -> #3 (&mm->mmap_sem){++++++}: [21002.712080] lock_acquire+0xc9/0x230 [21002.716661] __might_fault+0x70/0xa0 [21002.721241] _copy_to_user+0x23/0x70 [21002.725814] filldir+0xa7/0x110 [21002.729988] xfs_dir2_sf_getdents.isra.10+0x20c/0x2c0 [xfs] [21002.736840] xfs_readdir+0x1fa/0x2c0 [xfs] [21002.742042] xfs_file_readdir+0x30/0x40 [xfs] [21002.747485] iterate_dir+0x17a/0x1a0 [21002.752057] SyS_getdents+0xb0/0x160 [21002.756638] entry_SYSCALL_64_fastpath+0x1f/0xbe [21002.762371] [21002.762371] -> #2 (&type->i_mutex_dir_key#3){++++++}: [21002.769661] lock_acquire+0xc9/0x230 [21002.774239] down_read+0x51/0xb0 [21002.778429] lookup_slow+0xde/0x210 [21002.782903] walk_component+0x160/0x250 [21002.787765] link_path_walk+0x1a6/0x610 [21002.792625] path_openat+0xe4/0xd50 [21002.797100] do_filp_open+0x91/0x100 [21002.801673] file_open_name+0xf5/0x130 [21002.806429] filp_open+0x33/0x50 [21002.810620] kernel_read_file_from_path+0x39/0x80 [21002.816459] _request_firmware+0x39f/0x880 [21002.821610] request_firmware_direct+0x37/0x50 [21002.827151] request_microcode_fw+0x64/0xe0 [21002.832401] reload_store+0xf7/0x180 [21002.836974] dev_attr_store+0x18/0x30 [21002.841641] sysfs_kf_write+0x44/0x60 [21002.846318] kernfs_fop_write+0x113/0x1a0 [21002.851374] __vfs_write+0x37/0x170 [21002.855849] vfs_write+0xc7/0x1c0 [21002.860128] SyS_write+0x58/0xc0 [21002.864313] do_syscall_64+0x6c/0x1f0 [21002.868973] return_from_SYSCALL_64+0x0/0x7a [21002.874317] [21002.874317] -> #1 (microcode_mutex){+.+.+.}: [21002.880748] lock_acquire+0xc9/0x230 [21002.885322] __mutex_lock+0x88/0x960 [21002.889894] mutex_lock_nested+0x1b/0x20 [21002.894854] microcode_init+0xbb/0x208 [21002.899617] do_one_initcall+0x51/0x1a9 [21002.904481] kernel_init_freeable+0x208/0x2a7 [21002.909922] kernel_init+0xe/0x104 [21002.914298] ret_from_fork+0x2a/0x40 [21002.918867] [21002.918867] -> #0 (cpu_hotplug_lock.rw_sem){++++++}: [21002.926058] __lock_acquire+0x153c/0x1550 [21002.931112] lock_acquire+0xc9/0x230 [21002.935688] cpus_read_lock+0x4b/0x90 [21002.940353] drain_all_stock.part.35+0x18/0x140 [21002.945987] try_charge+0x3ab/0x6e0 [21002.950460] mem_cgroup_try_charge+0x7f/0x2c0 [21002.955902] shmem_getpage_gfp+0x25f/0x1050 [21002.961149] shmem_fault+0x96/0x200 [21002.965621] __do_fault+0x1e/0xa0 [21002.969905] __handle_mm_fault+0x9c3/0xe00 [21002.975056] handle_mm_fault+0x16e/0x380 [21002.980013] __do_page_fault+0x24a/0x530 [21002.984968] do_page_fault+0x30/0x80 [21002.989537] page_fault+0x28/0x30 [21002.993812] [21002.993812] other info that might help us debug this: [21002.993812] [21003.002744] Chain exists of: [21003.002744] cpu_hotplug_lock.rw_sem --> &type->i_mutex_dir_key#3 --> &mm->mmap_sem [21003.002744] [21003.016238] Possible unsafe locking scenario: [21003.016238] [21003.022843] CPU0 CPU1 [21003.027896] ---- ---- [21003.032948] lock(&mm->mmap_sem); [21003.036741] lock(&type->i_mutex_dir_key#3); [21003.044419] lock(&mm->mmap_sem); [21003.051025] lock(cpu_hotplug_lock.rw_sem); [21003.055788] [21003.055788] *** DEADLOCK *** [21003.055788] [21003.062393] 2 locks held by a.out/4771: [21003.066675] #0: (&mm->mmap_sem){++++++}, at: [] __do_page_fault+0x175/0x530 [21003.076391] #1: (percpu_charge_mutex){+.+...}, at: [] try_charge+0x397/0x6e0 [21003.086198] [21003.086198] stack backtrace: [21003.091059] CPU: 6 PID: 4771 Comm: a.out Not tainted 4.13.0-rc3-next-20170807 #12 [21003.099409] Hardware name: Dell Inc. PowerEdge M520/0DW6GX, BIOS 2.4.2 02/03/2015 [21003.107766] Call Trace: [21003.110495] dump_stack+0x85/0xc9 [21003.114190] print_circular_bug+0x1f9/0x207 [21003.118854] __lock_acquire+0x153c/0x1550 [21003.123327] lock_acquire+0xc9/0x230 [21003.127313] ? drain_all_stock.part.35+0x18/0x140 [21003.132563] cpus_read_lock+0x4b/0x90 [21003.136652] ? drain_all_stock.part.35+0x18/0x140 [21003.141900] drain_all_stock.part.35+0x18/0x140 [21003.146954] try_charge+0x3ab/0x6e0 [21003.150846] mem_cgroup_try_charge+0x7f/0x2c0 [21003.155705] shmem_getpage_gfp+0x25f/0x1050 [21003.160374] shmem_fault+0x96/0x200 [21003.164263] ? __lock_acquire+0x2fb/0x1550 [21003.168832] ? __lock_acquire+0x2fb/0x1550 [21003.173402] __do_fault+0x1e/0xa0 [21003.177097] __handle_mm_fault+0x9c3/0xe00 [21003.181669] handle_mm_fault+0x16e/0x380 [21003.186045] ? handle_mm_fault+0x49/0x380 [21003.190518] __do_page_fault+0x24a/0x530 [21003.194895] do_page_fault+0x30/0x80 [21003.198883] page_fault+0x28/0x30 [21003.202593] RIP: 0033:0x400886 [21003.205998] RSP: 002b:00007fff81d84d20 EFLAGS: 00010206 [21003.211827] RAX: 00007fc763bb7000 RBX: 0000000000000000 RCX: 0000000000001000 [21003.219789] RDX: 0000000006362000 RSI: 0000000019000000 RDI: 00007fc75d855000 [21003.227751] RBP: 00007fff81d84d50 R08: ffffffffffffffff R09: 0000000000000000 [21003.235713] R10: 00007fff81d84a30 R11: 00007fc7769445d0 R12: 0000000000400750 [21003.243681] R13: 00007fff81d84f70 R14: 0000000000000000 R15: 0000000000000000 -- Regards, Artem