Re: [RFC PATCH 1/2] mm, vmscan: account the number of isolated pages per zone
From: Michal Hocko <mhocko@kernel.org>
Date: 2017-02-07 21:12:19
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lkml
On Mon 06-02-17 11:39:18, Michal Hocko wrote:
On Sun 05-02-17 19:43:07, Tetsuo Handa wrote:quoted
Michal Hocko wrote: I got same warning with ext4. Maybe we need to check carefully. [ 511.215743] ===================================================== [ 511.218003] WARNING: RECLAIM_FS-safe -> RECLAIM_FS-unsafe lock order detected [ 511.220031] 4.10.0-rc6-next-20170202+ #500 Not tainted [ 511.221689] ----------------------------------------------------- [ 511.223579] a.out/49302 [HC0[0]:SC0[0]:HE1:SE1] is trying to acquire: [ 511.225533] (cpu_hotplug.dep_map){++++++}, at: [<ffffffff810a1477>] get_online_cpus+0x37/0x80 [ 511.227795] [ 511.227795] and this task is already holding: [ 511.230082] (jbd2_handle){++++-.}, at: [<ffffffff813a8be7>] start_this_handle+0x1a7/0x590 [ 511.232592] which would create a new lock dependency: [ 511.234192] (jbd2_handle){++++-.} -> (cpu_hotplug.dep_map){++++++} [ 511.235966] [ 511.235966] but this new dependency connects a RECLAIM_FS-irq-safe lock: [ 511.238563] (jbd2_handle){++++-.} [ 511.238564] [ 511.238564] ... which became RECLAIM_FS-irq-safe at: [ 511.242078] [ 511.242084] [<ffffffff811089db>] __lock_acquire+0x34b/0x1640 [ 511.244495] [<ffffffff8110a119>] lock_acquire+0xc9/0x250 [ 511.246697] [<ffffffff813b3525>] jbd2_log_wait_commit+0x55/0x1d0[...]quoted
[ 511.276216] to a RECLAIM_FS-irq-unsafe lock: [ 511.278128] (cpu_hotplug.dep_map){++++++} [ 511.278130] [ 511.278130] ... which became RECLAIM_FS-irq-unsafe at: [ 511.281809] ... [ 511.281811] [ 511.282598] [<ffffffff81108141>] mark_held_locks+0x71/0x90 [ 511.284854] [<ffffffff8110ab6f>] lockdep_trace_alloc+0x6f/0xd0 [ 511.287218] [<ffffffff812744c8>] kmem_cache_alloc_node_trace+0x48/0x3b0 [ 511.289755] [<ffffffff810cfa65>] __smpboot_create_thread.part.2+0x35/0xf0 [ 511.292329] [<ffffffff810d0026>] smpboot_create_threads+0x66/0x90[...]quoted
[ 511.317867] other info that might help us debug this: [ 511.317867] [ 511.320920] Possible interrupt unsafe locking scenario: [ 511.320920] [ 511.323218] CPU0 CPU1 [ 511.324622] ---- ---- [ 511.325973] lock(cpu_hotplug.dep_map); [ 511.327246] local_irq_disable(); [ 511.328870] lock(jbd2_handle); [ 511.330483] lock(cpu_hotplug.dep_map); [ 511.332259] <Interrupt> [ 511.333187] lock(jbd2_handle);Peter, is there any way how to tell the lockdep that this is in fact reclaim safe? The direct reclaim only does the trylock and backs off so we cannot deadlock here. Or am I misinterpreting the trace?
This is moot - http://lkml.kernel.org/r/20170207201950.20482-1-mhocko@kernel.org -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>