Re: [PATCH] vmscan: don't use return value trick when oom_killer_disabled

[Rafael J. Wysocki]

On Thursday, September 02, 2010, Minchan Kim wrote:
> M. Vefa Bicakci reported 2.6.35 kernel hang up when hibernation on his
> 32bit 3GB mem machine. (https://bugzilla.kernel.org/show_bug.cgi?id=16771)
> Also he was bisected first bad commit is below
> 
>   commit bb21c7ce18eff8e6e7877ca1d06c6db719376e3c
>   Author: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
>   Date:   Fri Jun 4 14:15:05 2010 -0700
> 
>      vmscan: fix do_try_to_free_pages() return value when priority==0 reclaim failure
> 
> At first impression, this seemed very strange because the above commit only
> chenged function return value and hibernate_preallocate_memory() ignore
> return value of shrink_all_memory(). But it's related.
> 
> Now, page allocation from hibernation code may enter infinite loop if
> the system has highmem.
> 
> The reasons are two. 1) hibernate_preallocate_memory() call
> alloc_pages() wrong order

This isn't the case, as explained here: http://lkml.org/lkml/2010/9/1/316 .

The ordering of calls is correct, but it's better to check if there are any
non-highmem pages to allocate from before the last call (for performance
reasons, but that also would eliminate the failure in question).

Thanks,
Rafael
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