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SubjectRe: + shmem-fix-faulting-into-a-hole-while-its-punched-take-2.patch added to -mm tree
On Thu, 10 Jul 2014, Sasha Levin wrote:
> On 07/10/2014 08:46 AM, Sasha Levin wrote:
> > On 07/10/2014 03:37 AM, Hugh Dickins wrote:
> >> > I do think that the most useful thing you could do at the moment,
> >> > is to switch away from running trinity on -next temporarily, and
> >> > run it instead on Linus's current git or on 3.16-rc4, but with
> >> > f00cdc6df7d7 reverted and my "take 2" inserted in its place.
> >> >
> >> > That tree would also include Heiko's seq_buf_alloc() patch, which
> >> > trinity on -next has cast similar doubt upon: at present, we do
> >> > not know if Heiko's patch and my patch are bad in themselves,
> >> > or exposing other bugs in 3.16-rc, or exposing bugs in -next.
> > Funny enough, Linus's tree doesn't even boot properly here. It's
> > going to take longer than I expected...

Thanks a lot for getting down to this so quickly.

>
> While I'm failing to reproduce the mountinfo issue on Linus's tree,

That's good news for Heiko's patch:
no reason to rush and revert it, I guess.

> the shmem_fallocate one reproduces rather easily.

"Good" news of the opposite kind ;) Very useful to know that.

>
> I've reverted your original fix and applied the "take 2" one as you
> suggested, there are no other significant changes on top on Linus's
> tree in this case (just Heiko's test patch and some improvements to
> what gets printed on hung tasks plus an assortment on unrelated fixes
> that are present in next).

Just right, thanks.

>
> The same structure of locks that was analysed in -next exists here
> as well:
>
> Triggered here:
>
> [ 364.601210] INFO: task trinity-c214:9083 blocked for more than 120 seconds.
> [ 364.605498] Not tainted 3.16.0-rc4-sasha-00069-g615ded7-dirty #793
> [ 364.609705] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 364.614939] trinity-c214 D 0000000000000002 13528 9083 8490 0x00000000
> [ 364.619414] ffff880018757ce8 0000000000000002 ffffffff91a01d70 0000000000000001
> [ 364.624540] ffff880018757fd8 00000000001d7740 00000000001d7740 00000000001d7740
> [ 364.629378] ffff880006428000 ffff880018758000 ffff880018757cd8 ffff880031fdc210
> [ 364.650601] Call Trace:
> [ 364.652252] schedule (kernel/sched/core.c:2832)
> [ 364.655337] schedule_preempt_disabled (kernel/sched/core.c:2859)
> [ 364.659287] mutex_lock_nested (kernel/locking/mutex.c:535 kernel/locking/mutex.c:587)
> [ 364.663131] ? shmem_fallocate (mm/shmem.c:1738)
> [ 364.666616] ? get_parent_ip (kernel/sched/core.c:2546)
> [ 364.670454] ? shmem_fallocate (mm/shmem.c:1738)
> [ 364.674159] shmem_fallocate (mm/shmem.c:1738)
> [ 364.676589] ? SyS_madvise (mm/madvise.c:334 mm/madvise.c:384 mm/madvise.c:534 mm/madvise.c:465)
> [ 364.678415] ? put_lock_stats.isra.12 (./arch/x86/include/asm/preempt.h:98 kernel/locking/lockdep.c:254)
> [ 364.680806] ? SyS_madvise (mm/madvise.c:334 mm/madvise.c:384 mm/madvise.c:534 mm/madvise.c:465)
> [ 364.684206] do_fallocate (include/linux/fs.h:1281 fs/open.c:299)
> [ 364.687313] SyS_madvise (mm/madvise.c:335 mm/madvise.c:384 mm/madvise.c:534 mm/madvise.c:465)
> [ 364.690343] ? context_tracking_user_exit (./arch/x86/include/asm/paravirt.h:809 (discriminator 2) kernel/context_tracking.c:184 (discriminator 2))
> [ 364.692913] ? trace_hardirqs_on (kernel/locking/lockdep.c:2607)
> [ 364.694450] tracesys (arch/x86/kernel/entry_64.S:543)
> [ 364.696034] 2 locks held by trinity-c214/9083:
> [ 364.697222] #0: (sb_writers#9){.+.+.+}, at: do_fallocate (fs/open.c:298)
> [ 364.700686] #1: (&sb->s_type->i_mutex_key#16){+.+.+.}, at: shmem_fallocate (mm/shmem.c:1738)
>
> Holding i_mutex and blocking on i_mmap_mutex:
>
> [ 367.615992] trinity-c100 R running task 13048 8967 8490 0x00000006
> [ 367.616039] ffff88001b903978 0000000000000002 0000000000000006 ffff880404666fd8
> [ 367.616075] ffff88001b903fd8 00000000001d7740 00000000001d7740 00000000001d7740
> [ 367.616113] ffff880007a40000 ffff88001b8f8000 ffff88001b903968 ffff88001b903fd8
> [ 367.616152] Call Trace:
> [ 367.616165] preempt_schedule_irq (./arch/x86/include/asm/paravirt.h:814 kernel/sched/core.c:2912)
> [ 367.616182] retint_kernel (arch/x86/kernel/entry_64.S:937)
> [ 367.616198] ? unmap_single_vma (mm/memory.c:1230 mm/memory.c:1277 mm/memory.c:1302 mm/memory.c:1348)
> [ 367.616213] ? unmap_single_vma (mm/memory.c:1297 mm/memory.c:1348)
> [ 367.616226] zap_page_range_single (include/linux/mmu_notifier.h:234 mm/memory.c:1429)
> [ 367.616240] ? get_parent_ip (kernel/sched/core.c:2546)
> [ 367.616260] ? unmap_mapping_range (mm/memory.c:2391)
> [ 367.616267] unmap_mapping_range (mm/memory.c:2316 mm/memory.c:2392)
> [ 367.616271] truncate_inode_page (mm/truncate.c:136 mm/truncate.c:180)
> [ 367.616281] shmem_undo_range (mm/shmem.c:429)
> [ 367.616289] shmem_truncate_range (mm/shmem.c:528)
> [ 367.616296] shmem_fallocate (mm/shmem.c:1749)
> [ 367.616301] ? SyS_madvise (mm/madvise.c:334 mm/madvise.c:384 mm/madvise.c:534 mm/madvise.c:465)
> [ 367.616307] ? put_lock_stats.isra.12 (./arch/x86/include/asm/preempt.h:98 kernel/locking/lockdep.c:254)
> [ 367.616314] ? SyS_madvise (mm/madvise.c:334 mm/madvise.c:384 mm/madvise.c:534 mm/madvise.c:465)
> [ 367.616320] do_fallocate (include/linux/fs.h:1281 fs/open.c:299)
> [ 367.616326] SyS_madvise (mm/madvise.c:335 mm/madvise.c:384 mm/madvise.c:534 mm/madvise.c:465)
> [ 367.616333] ? context_tracking_user_exit (./arch/x86/include/asm/paravirt.h:809 (discriminator 2) kernel/context_tracking.c:184 (discriminator 2))
> [ 367.616340] ? trace_hardirqs_on (kernel/locking/lockdep.c:2607)
> [ 367.616345] tracesys (arch/x86/kernel/entry_64.S:543)
>
> And finally, (not) holding the i_mmap_mutex:

I don't understand what prompts you to show this particular task.
I imagine the dump shows lots of other tasks which are waiting to get an
i_mmap_mutex, and quite a lot of other tasks which are neither waiting
for nor holding an i_mmap_mutex.

Why are you showing this one in particular? Because it looks like the
one you fingered yesterday? But I didn't see a good reason to finger
that one either.

Mind you, I'm still baffled by the oops on testing PageAnon that you
got a few days ago in zap_pte_range(), so maybe zap_pte_range() does
deserve special attention.

>
> [ 367.638911] trinity-c190 R running task 12680 9059 8490 0x00000004
> [ 367.638928] ffff8800193db828 0000000000000002 0000000000000030 0000000000000000
> [ 367.638937] ffff8800193dbfd8 00000000001d7740 00000000001d7740 00000000001d7740
> [ 367.638943] ffff8800048eb000 ffff8800193d0000 ffff8800193db818 ffff8800193dbfd8
> [ 367.638950] Call Trace:
> [ 367.638952] [<ffffffff8e5170f4>] preempt_schedule_irq+0x84/0x100
> [ 367.638956] [<ffffffff8e51ec50>] retint_kernel+0x20/0x30
> [ 367.638960] [<ffffffff8b290c36>] ? free_hot_cold_page+0x1c6/0x1f0
> [ 367.638962] [<ffffffff8b291566>] free_hot_cold_page_list+0x126/0x1a0
> [ 367.638974] [<ffffffff8b29702e>] release_pages+0x21e/0x250
> [ 367.638989] [<ffffffff8b2cf0c5>] free_pages_and_swap_cache+0x55/0xc0
> [ 367.638999] [<ffffffff8b2b68ac>] tlb_flush_mmu_free+0x4c/0x60
> [ 367.639012] [<ffffffff8b2b8dd1>] zap_pte_range+0x491/0x4f0
> [ 367.639019] [<ffffffff8b2b92ce>] unmap_single_vma+0x49e/0x4c0
> [ 367.639025] [<ffffffff8b2b9675>] unmap_vmas+0x65/0x90
> [ 367.639029] [<ffffffff8b2c3344>] exit_mmap+0xd4/0x180
> [ 367.639032] [<ffffffff8b15c4ab>] mmput+0x5b/0xf0
> [ 367.639038] [<ffffffff8b163043>] do_exit+0x3a3/0xc80
> [ 367.639041] [<ffffffff8bb46d37>] ? debug_smp_processor_id+0x17/0x20
> [ 367.639044] [<ffffffff8b1c2fae>] ? put_lock_stats.isra.12+0xe/0x30
> [ 367.639047] [<ffffffff8e51d100>] ? _raw_spin_unlock_irq+0x30/0x70
> [ 367.639051] [<ffffffff8b1639f4>] do_group_exit+0x84/0xd0
> [ 367.639055] [<ffffffff8b177657>] get_signal_to_deliver+0x807/0x910
> [ 367.639059] [<ffffffff8b1a6eb8>] ? vtime_account_user+0x98/0xb0
> [ 367.639063] [<ffffffff8b0706c7>] do_signal+0x57/0x9a0
> [ 367.639066] [<ffffffff8b1a6eb8>] ? vtime_account_user+0x98/0xb0
> [ 367.639070] [<ffffffff8b19f228>] ? preempt_count_sub+0xd8/0x130
> [ 367.639072] [<ffffffff8b2848d5>] ? context_tracking_user_exit+0x1b5/0x260
> [ 367.639078] [<ffffffff8bb46d13>] ? __this_cpu_preempt_check+0x13/0x20
> [ 367.639081] [<ffffffff8b1c5df4>] ? trace_hardirqs_on_caller+0x1f4/0x290
> [ 367.639087] [<ffffffff8b07104a>] do_notify_resume+0x3a/0xb0
> [ 367.639089] [<ffffffff8e51e02a>] int_signal+0x12/0x17

I'm not sure whether I should ask you to attach the full dump or not:
I learnt very little from yesterday's 11MB, and from what you say this
one will look very similar. Oh, I'd better ask for it, but I bet you
process these things much faster than I can manage.

Thanks,
Hugh


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