Rafael, this log mean hibernate_preallocate_memory() has a bug.
It allocate memory as following order.
1. preallocate_image_highmem() (i.e. __GFP_HIGHMEM)
2. preallocate_image_memory() (i.e. GFP_KERNEL)
3. preallocate_highmem_fraction (i.e. __GFP_HIGHMEM)
4. preallocate_image_memory() (i.e. GFP_KERNEL)
But, please imazine following scenario (as Vefa's scenario).
- system has 3GB memory. 1GB is normal. 2GB is highmem.
- all normal memory is free
- 1.5GB memory of highmem are used for tmpfs. rest 500MB is free.
At that time, hibernate_preallocate_memory() works as following.
1. call preallocate_image_highmem(1GB)
2. call preallocate_image_memory(500M) total 1.5GB allocated
3. call preallocate_highmem_fraction(660M) total 2.2GB allocated
then, all of normal zone memory was exhaust. next preallocate_image_memory()
makes OOM, and oom_killer_disabled makes infinite loop.
(oom_killer_disabled careless is vmscan bug. I'll fix it soon)
The problem is, alloc_pages(__GFP_HIGHMEM) -> alloc_pages(GFP_KERNEL) is
wrong order. alloc_pages(__GFP_HIGHMEM) may allocate page from lower zone.
then, next alloc_pages(GFP_KERNEL) lead to OOM.
Please consider alloc_pages(GFP_KERNEL) -> alloc_pages(__GFP_HIGHMEM) order.
Even though vmscan fix can avoid infinite loop, OOM situation might makes
big slow down on highmem machine. It seems no good.
Thanks.
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