Patchwork [09/16] mm: use vm_unmapped_area() in hugetlbfs on i386 architecture

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Submitter Michel Lespinasse
Date Nov. 5, 2012, 10:47 p.m.
Message ID <1352155633-8648-10-git-send-email-walken@google.com>
Download mbox | patch
Permalink /patch/197349/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Michel Lespinasse - Nov. 5, 2012, 10:47 p.m.
Update the i386 hugetlb_get_unmapped_area function to make use of
vm_unmapped_area() instead of implementing a brute force search.

Signed-off-by: Michel Lespinasse <walken@google.com>

---
 arch/x86/mm/hugetlbpage.c |  130 +++++++++------------------------------------
 1 files changed, 25 insertions(+), 105 deletions(-)
Rik van Riel - Nov. 5, 2012, 11:07 p.m.
On 11/05/2012 05:47 PM, Michel Lespinasse wrote:
> Update the i386 hugetlb_get_unmapped_area function to make use of
> vm_unmapped_area() instead of implementing a brute force search.
>
> Signed-off-by: Michel Lespinasse <walken@google.com>

Reviewed-by: Rik van Riel <riel@redhat.com>

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Andrew Morton - Nov. 6, 2012, 10:38 p.m.
On Mon,  5 Nov 2012 14:47:06 -0800
Michel Lespinasse <walken@google.com> wrote:

> Update the i386 hugetlb_get_unmapped_area function to make use of
> vm_unmapped_area() instead of implementing a brute force search.

The x86_64 coloring "fix" wasn't copied into i386?
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Rik van Riel - Nov. 6, 2012, 10:48 p.m.
On 11/06/2012 05:38 PM, Andrew Morton wrote:
> On Mon,  5 Nov 2012 14:47:06 -0800
> Michel Lespinasse <walken@google.com> wrote:
>
>> Update the i386 hugetlb_get_unmapped_area function to make use of
>> vm_unmapped_area() instead of implementing a brute force search.
>
> The x86_64 coloring "fix" wasn't copied into i386?

Only certain 64 bit AMD CPUs have that issue at all.

On x86, page coloring is really not much of an issue.

All the x86-64 patch does is make the x86-64 page
coloring code behave the same way page coloring
does on MIPS, SPARC, ARM, PA-RISC and others...
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Patch

diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 937bff5cdaa7..c00c4a4cd564 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -274,42 +274,15 @@  static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 		unsigned long pgoff, unsigned long flags)
 {
 	struct hstate *h = hstate_file(file);
-	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
-	unsigned long start_addr;
-
-	if (len > mm->cached_hole_size) {
-	        start_addr = mm->free_area_cache;
-	} else {
-	        start_addr = TASK_UNMAPPED_BASE;
-	        mm->cached_hole_size = 0;
-	}
-
-full_search:
-	addr = ALIGN(start_addr, huge_page_size(h));
-
-	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
-		/* At this point:  (!vma || addr < vma->vm_end). */
-		if (TASK_SIZE - len < addr) {
-			/*
-			 * Start a new search - just in case we missed
-			 * some holes.
-			 */
-			if (start_addr != TASK_UNMAPPED_BASE) {
-				start_addr = TASK_UNMAPPED_BASE;
-				mm->cached_hole_size = 0;
-				goto full_search;
-			}
-			return -ENOMEM;
-		}
-		if (!vma || addr + len <= vma->vm_start) {
-			mm->free_area_cache = addr + len;
-			return addr;
-		}
-		if (addr + mm->cached_hole_size < vma->vm_start)
-		        mm->cached_hole_size = vma->vm_start - addr;
-		addr = ALIGN(vma->vm_end, huge_page_size(h));
-	}
+	struct vm_unmapped_area_info info;
+
+	info.flags = 0;
+	info.length = len;
+	info.low_limit = TASK_UNMAPPED_BASE;
+	info.high_limit = TASK_SIZE;
+	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
+	info.align_offset = 0;
+	return vm_unmapped_area(&info);
 }
 
 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
@@ -317,83 +290,30 @@  static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 		unsigned long pgoff, unsigned long flags)
 {
 	struct hstate *h = hstate_file(file);
-	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
-	unsigned long base = mm->mmap_base;
-	unsigned long addr = addr0;
-	unsigned long largest_hole = mm->cached_hole_size;
-	unsigned long start_addr;
-
-	/* don't allow allocations above current base */
-	if (mm->free_area_cache > base)
-		mm->free_area_cache = base;
-
-	if (len <= largest_hole) {
-	        largest_hole = 0;
-		mm->free_area_cache  = base;
-	}
-try_again:
-	start_addr = mm->free_area_cache;
-
-	/* make sure it can fit in the remaining address space */
-	if (mm->free_area_cache < len)
-		goto fail;
-
-	/* either no address requested or can't fit in requested address hole */
-	addr = (mm->free_area_cache - len) & huge_page_mask(h);
-	do {
-		/*
-		 * Lookup failure means no vma is above this address,
-		 * i.e. return with success:
-		 */
-		vma = find_vma(mm, addr);
-		if (!vma)
-			return addr;
+	struct vm_unmapped_area_info info;
+	unsigned long addr;
 
-		if (addr + len <= vma->vm_start) {
-			/* remember the address as a hint for next time */
-		        mm->cached_hole_size = largest_hole;
-		        return (mm->free_area_cache = addr);
-		} else if (mm->free_area_cache == vma->vm_end) {
-			/* pull free_area_cache down to the first hole */
-			mm->free_area_cache = vma->vm_start;
-			mm->cached_hole_size = largest_hole;
-		}
+	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+	info.length = len;
+	info.low_limit = PAGE_SIZE;
+	info.high_limit = mm->mmap_base;
+	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
+	info.align_offset = 0;
+	addr = vm_unmapped_area(&info);
 
-		/* remember the largest hole we saw so far */
-		if (addr + largest_hole < vma->vm_start)
-		        largest_hole = vma->vm_start - addr;
-
-		/* try just below the current vma->vm_start */
-		addr = (vma->vm_start - len) & huge_page_mask(h);
-	} while (len <= vma->vm_start);
-
-fail:
-	/*
-	 * if hint left us with no space for the requested
-	 * mapping then try again:
-	 */
-	if (start_addr != base) {
-		mm->free_area_cache = base;
-		largest_hole = 0;
-		goto try_again;
-	}
 	/*
 	 * A failed mmap() very likely causes application failure,
 	 * so fall back to the bottom-up function here. This scenario
 	 * can happen with large stack limits and large mmap()
 	 * allocations.
 	 */
-	mm->free_area_cache = TASK_UNMAPPED_BASE;
-	mm->cached_hole_size = ~0UL;
-	addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
-			len, pgoff, flags);
-
-	/*
-	 * Restore the topdown base:
-	 */
-	mm->free_area_cache = base;
-	mm->cached_hole_size = ~0UL;
+	if (addr & ~PAGE_MASK) {
+		VM_BUG_ON(addr != -ENOMEM);
+		info.flags = 0;
+		info.low_limit = TASK_UNMAPPED_BASE;
+		info.high_limit = TASK_SIZE;
+		addr = vm_unmapped_area(&info);
+	}
 
 	return addr;
 }