Re: [Bug 56881] New: MAP_HUGETLB mmap fails for certain sizes

[Johannes Weiner <hannes@cmpxchg.org>]

On Wed, Apr 24, 2013 at 11:16:39AM -0400, Naoya Horiguchi wrote:
> On Wed, Apr 24, 2013 at 04:14:54AM -0400, Johannes Weiner wrote:
> > @@ -491,10 +491,13 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
> >  
> >  	sprintf (name, "SYSV%08x", key);
> >  	if (shmflg & SHM_HUGETLB) {
> > +		unsigned int hugesize;
> > +
> >  		/* hugetlb_file_setup applies strict accounting */
> >  		if (shmflg & SHM_NORESERVE)
> >  			acctflag = VM_NORESERVE;
> > -		file = hugetlb_file_setup(name, 0, size, acctflag,
> > +		hugesize = ALIGN(size, huge_page_size(&default_hstate));
> > +		file = hugetlb_file_setup(name, hugesize, acctflag,
> >  				  &shp->mlock_user, HUGETLB_SHMFS_INODE,
> >  				(shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
> >  	} else {
> 
> Would it be better to find proper hstate instead of using default_hstate?

You are probably right, I guess we can't assume default_hstate anymore
after page_size_log can be passed in.

Can we have hugetlb_file_setup() return an adjusted length, or an
alignment requirement?

Or pull the hstate lookup into the callsites (since they pass in
page_size_log to begin with)?

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