[LTP] [PATCH] lib: memutils: don't pollute entire system memory to avoid OoM

[Martin Doucha]

On 24. 06. 21 16:00, Li Wang wrote:
> FYI, Another related analysis:
> https://lists.linux.it/pipermail/ltp/2021-April/021903.html
> <https://lists.linux.it/pipermail/ltp/2021-April/021903.html>
> 
> The mmap() behavior changed in GUESS mode from commit 8c7829b04c523cd,
> we can NOT receive MAP_FAILED on ENOMEM in userspace anymore,unless 
> the process one-time allocating memory larger than "total_ram+
> total_swap" explicitly.
> 
> Which also means the MAP_FAILED check lose effect permanently in line#51:
> https://github.com/linux-test-project/ltp/blob/master/lib/tst_memutils.c#L51
> <https://github.com/linux-test-project/ltp/blob/master/lib/tst_memutils.c#L51>

I'm pretty sure that 32bit x86 kernel with PAE and more than 3GB of RAM
will give you MAP_FAILED because you'll run out of available address
space before you run out of physical memory.

-- 
Martin Doucha   mdoucha@suse.cz
QA Engineer for Software Maintenance
SUSE LINUX, s.r.o.
CORSO IIa
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