On Fri, 10 Feb 2017, Michal Hocko wrote:
On Thu 09-02-17 12:53:02, Davidlohr Bueso wrote:
The SHM_HUGE_* stuff was introduced in:
42d7395feb5 (mm: support more pagesizes for MAP_HUGETLB/SHM_HUGETLB)
It unnecessarily adds another layer, specific to sysv shm, without
anything special about it: the macros are identical to the MAP_HUGE_*
stuff, which in turn does correctly describe the hugepage subsystem.
One example of the problems with extra layers what this patch fixes:
mmap_pgoff() should never be using SHM_HUGE_* logic. It is obviously
harmless but it would still be grand to get rid of it -- although
now in the manpages I don't see that happening.
Can we just drop SHM_HUGE_MASK altogether? It is not exported in uapi
headers AFAICS.
Yeah that was my original idea, however I noticed that shmget.2 mentions
kernel internals as part of SHM_HUGE_{2MB,1GB}, ie: SHM_HUGE_SHIFT. So
dropping _MASK doesn't make sense if we are going to keep _SHIFT.
Thanks,
Davidlohr
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