Re: [PATCH] Fix virtual address handling in hugetlb fault
From: KAMEZAWA Hiroyuki <hidden>
Date: 2011-11-22 00:33:53
On Mon, 21 Nov 2011 14:27:20 -0800 Andrew Morton [off-list ref] wrote:
On Mon, 21 Nov 2011 19:48:32 +0900 KAMEZAWA Hiroyuki [off-list ref] wrote:quoted
quoted
From 7c29389be2890c6b6934a80b4841d07a7014fe26 Mon Sep 17 00:00:00 2001From: KAMEZAWA Hiroyuki <redacted> Date: Mon, 21 Nov 2011 19:45:27 +0900 Subject: [PATCH] Fix virtual address handling in hugetlb fault handle_mm_fault() passes 'faulted' address to hugetlb_fault(). Then, the address is not aligned to hugepage boundary. Most of functions for hugetlb pages are aware of that and calculate an alignment by itself. Some functions as copy_user_huge_page(), and clear_huge_page() doesn't handle alignment by themselves. This patch make hugeltb_fault() to calculate the alignment and pass aligned addresss (top address of a faulted hugepage) to functions.Does this actually fix any known user-visible misbehaviour?
I just found this at reading codes. And I know 'vaddr' is ignored in most of per-arch implemantation of clear_user_highpage(). It seems, in some arch, vaddr is used for flushing cache. Now, CONFIG_HUGETLBFS can be set on x86,powerpc,ia64,mips,sh,sparc,tile. (by grep) it seems mips and sh uses vaddr in clear_user_(high)page.
It sounds like the code is masking addresses in a lot of different places. It would be better to do it once, at the top level. Perhaps this patch makes some of the existing masking obsolete?
I think so. I'd like to check it and post an additional fix if this patch goes.
quoted hunk ↗ jump to hunk
quoted
index bb28a5f..af37337 100644--- a/mm/hugetlb.c +++ b/mm/hugetlb.c@@ -2629,6 +2629,8 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, static DEFINE_MUTEX(hugetlb_instantiation_mutex); struct hstate *h = hstate_vma(vma); + address = address & huge_page_mask(h);--- a/mm/hugetlb.c~mm-hugetlbc-fix-virtual-address-handling-in-hugetlb-fault-fix +++ a/mm/hugetlb.c@@ -2639,7 +2639,7 @@ int hugetlb_fault(struct mm_struct *mm, static DEFINE_MUTEX(hugetlb_instantiation_mutex); struct hstate *h = hstate_vma(vma); - address = address & huge_page_mask(h); + address &= huge_page_mask(h); ptep = huge_pte_offset(mm, address); if (ptep) {is a bit more readable, IMO.
Sure. Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>