Messages in this thread | | | From | KOSAKI Motohiro <> | Subject | Re: [PATCH] Create initial stack independent of PAGE_SIZE | Date | Fri, 12 Feb 2010 18:51:09 +0900 (JST) |
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> In message <20100212161305.73B2.A69D9226@jp.fujitsu.com> you wrote: > > > Currently we create the initial stack based on the PAGE_SIZE. This is > > > unnecessary. > > > > I don't think this is enough explanation. In past mail, you described > > why page size dependency is harmful. I hope you add it into the patch > > description. > > I don't think it's harmful, it's just irrelevant. Stack size is > independent of page size.
ok.
> > IOW, we don't need to change the unnecessary-but-non-harmful behavior. > > > > > > > > This creates this initial stack independent of the PAGE_SIZE. > > > > > > It also bumps up the number of 4k pages allocated from 20 to 32, to > > > align with 64K page systems. > > > > Why do we need page-aligning? Do you mean this code doesn't works on > > 128K (or more larger) page systems? > > If the "random" setting is not a common multiple of the 4k and 64k > pages, they will end up getting aligned differently, hence causing what > we are trying to avoid in the first place with this patch.
I see. ok, Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> > I should probably add this as a comment in the code comment?
probably, It's not big matter.
Thanks :)
> > Mikey > > > > > > > > > > > Signed-off-by: Michael Neuling <mikey@neuling.org> > > > --- > > > This is the second half of my original patch. This can be targeted for > > > 2.6.34 as it's just a cleanup. > > > > > > Tested on PPC64 with 4k and 64k pages. > > > > > > fs/exec.c | 4 +--- > > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > > > Index: linux-2.6-ozlabs/fs/exec.c > > > =================================================================== > > > --- linux-2.6-ozlabs.orig/fs/exec.c > > > +++ linux-2.6-ozlabs/fs/exec.c > > > @@ -554,8 +554,6 @@ static int shift_arg_pages(struct vm_are > > > return 0; > > > } > > > > > > -#define EXTRA_STACK_VM_PAGES 20 /* random */ > > > - > > > /* > > > * Finalizes the stack vm_area_struct. The flags and permissions are updat > ed, > > > * the stack is optionally relocated, and some extra space is added. > > > @@ -630,7 +628,7 @@ int setup_arg_pages(struct linux_binprm > > > goto out_unlock; > > > } > > > > > > - stack_expand = EXTRA_STACK_VM_PAGES * PAGE_SIZE; > > > + stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ > > > stack_size = vma->vm_end - vma->vm_start; > > > /* > > > * Align this down to a page boundary as expand_stack > > > > > >
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