RE: 6e543d5780e fixed a boot hang

[Lisa Du]

>-----Original Message-----
>From: Fengguang Wu [mailto:fengguang.wu@xxxxxxxxx]
>Sent: 2013年10月9日 22:12
>To: Lisa Du
>Cc: KOSAKI Motohiro; linux-mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
>Subject: 6e543d5780e fixed a boot hang
>
>Greetings,
>
>FYI, this commit seem to fix a boot hang problem here.
>
>commit 6e543d5780e36ff5ee56c44d7e2e30db3457a7ed
>Author: Lisa Du <cldu@xxxxxxxxxxx>
>Date:   Wed Sep 11 14:22:36 2013 -0700
>
>    mm: vmscan: fix do_try_to_free_pages() livelock
>
>
>        [    1.394871] pci 0000:00:02.0: Boot video device
>        [    1.395883] PCI: CLS 0 bytes, default 64
>
>In parent commit, it will hang right here.
>
>With this commit, it will continue to emit the below OOM messages (which is not a surprise to me because the boot test runs in a small
>memory KVM and the kconfig builds in lots of drivers).
I think you may meet the same issue as mine.
Direct reclaim loop forever with zone->all_unreclaimable = 0(as kswapd sleeps forever).
And at the boot stage, no one detect and terminate it, so you see the boot hang. 
After apply this patch, you see there's oom-killer invoked as direct reclaim would break when zone was unreclaimable.
>
>        [    1.631892] swapper/0 invoked oom-killer: gfp_mask=0x2000d0, order=1, oom_score_adj=0
>        [    1.633549] swapper/0 cpuset=/ mems_allowed=0
>        [    1.634443] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 3.12.0-rc4-00019-g8b5ede6 #126
>        [    1.635982] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
>        [    1.637088]  0000000000000002 ffff88001dd41b28 ffffffff82c8d78f ffff88001ef7c040
>        [    1.638955]  ffff88001dd41ba8 ffffffff82c8395f ffffffff83c54680 ffff88001dd41b60
>        [    1.640830]  ffffffff810f3f06 0000000000001eb4 0000000000000246 ffff88001dd41b98
>        [    1.642687] Call Trace:
>        [    1.643313]  [<ffffffff82c8d78f>] dump_stack+0x54/0x74
>        [    1.644331]  [<ffffffff82c8395f>] dump_header.isra.10+0x7a/0x1ba
>        [    1.645443]  [<ffffffff810f3f06>] ? lock_release_holdtime.part.27+0x4c/0x50
>        [    1.646685]  [<ffffffff810f795a>] ? lock_release+0x189/0x1d1
>        [    1.647744]  [<ffffffff811530a8>] out_of_memory+0x39e/0x3ee
>        [    1.648882]  [<ffffffff811579f5>] __alloc_pages_nodemask+0x668/0x7de
>        [    1.650385]  [<ffffffff8118eb53>] kmem_getpages+0x75/0x16c
>        [    1.651429]  [<ffffffff81190d20>] fallback_alloc+0x12c/0x1ea
>        [    1.652528]  [<ffffffff810f38e8>] ? trace_hardirqs_off+0xd/0xf
>        [    1.653627]  [<ffffffff81190be5>] ____cache_alloc_node+0x14a/0x159
>        [    1.654783]  [<ffffffff817059fb>] ? dma_debug_init+0x1ef/0x29a
>        [    1.655928]  [<ffffffff8119162c>] kmem_cache_alloc_trace+0x83/0x11a
>        [    1.657108]  [<ffffffff817059fb>] dma_debug_init+0x1ef/0x29a
>        [    1.658182]  [<ffffffff841ac38b>] pci_iommu_init+0x16/0x52
>        [    1.659263]  [<ffffffff841ac375>] ? iommu_setup+0x27d/0x27d
>        [    1.660342]  [<ffffffff810020d2>] do_one_initcall+0x93/0x137
>        [    1.661415]  [<ffffffff810bd300>] ? param_set_charp+0x92/0xd8
>        [    1.662503]  [<ffffffff810bd52e>] ? parse_args+0x189/0x247
>        [    1.663555]  [<ffffffff8419fed1>] kernel_init_freeable+0x15e/0x1df
>        [    1.664724]  [<ffffffff8419f729>] ? do_early_param+0x88/0x88
>        [    1.665814]  [<ffffffff82c77867>] ? rest_init+0xdb/0xdb
>        [    1.666824]  [<ffffffff82c77875>] kernel_init+0xe/0xdb
>        [    1.667824]  [<ffffffff82cbc57c>] ret_from_fork+0x7c/0xb0
>        [    1.668911]  [<ffffffff82c77867>] ? rest_init+0xdb/0xdb
>        [    1.669925] Mem-Info:
>        [    1.670508] Node 0 DMA per-cpu:
>
>Thanks,
>Fengguang
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