On Mon, Jun 02, 2014 at 02:53:34PM -0700, Dave Hansen wrote:
> On 06/02/2014 02:52 PM, Naoya Horiguchi wrote:
> > What version is this patchset based on?
> > Recently I comprehensively rewrote page table walker (from the same motivation
> > as yours) and the patchset is now in linux-mm. I guess most of your patchset
> > (I've not read them yet) conflict with this patchset.
> > So could you take a look on it?
>
> It's on top of a version of Linus's from the last week. I'll take a
> look at how it sits on top of -mm.
I've looked over your series, but unfortunately most of works (patch 1, 2, 3,
5, 6, 7) were already done or we don't have to do it in current linux-mm code.
Problems you try to handle in these patches come from current code's poor
design of page table walker, worst thing is that we do vma-loop inside pgd loop.
I know you tried harder to make things better, but I don't think it make sense
to maintain current bad base code for long.
As for patch 4, yes, we can apply page table walker do_mincore() and I have
a patch applicable onto linux-mm code (attached). And for other potential
page walk users, I'm investigating whether we can really apply page table
walker (some caller doesn't hold mmap_sem, so can't simply apply it.)
And for patch 8, 9, and 10, I don't think it's good idea to add a new callback
which can handle both pmd and pte (because they are essentially differnt thing).
But the underneath idea of doing pmd_trans_huge_lock() in the common code in
walk_single_entry_locked() looks nice to me. So it would be great if we can do
the same thing in walk_pmd_range() (of linux-mm) to reduce code in callbacks.
Thanks,
Naoya Horiguchi
---
>From d73b28adddd43bf29222eda86a851662bee8ef12 Mon Sep 17 00:00:00 2001
Date: Tue, 3 Jun 2014 00:06:26 -0400
Subject: [PATCH -mm] mincore: apply page table walker on do_mincore()
This patch makes do_mincore() use walk_page_vma(), which reduces the lines
of code by using common page table walk code.
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
mm/mincore.c | 196 +++++++++++++++++++++--------------------------------------
1 file changed, 70 insertions(+), 126 deletions(-)
diff --git a/mm/mincore.c b/mm/mincore.c
index 725c80961048..f292f5bea8e2 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -19,38 +19,27 @@
#include <asm/uaccess.h>
#include <asm/pgtable.h>
-static void mincore_hugetlb_page_range(struct vm_area_struct *vma,
- unsigned long addr, unsigned long end,
- unsigned char *vec)
+static int mincore_hugetlb(pte_t *pte, unsigned long addr,
+ unsigned long end, struct mm_walk *walk)
{
+ int err = 0;
#ifdef CONFIG_HUGETLB_PAGE
- struct hstate *h;
+ unsigned char present;
+ unsigned char *vec = walk->private;
- h = hstate_vma(vma);
- while (1) {
- unsigned char present;
- pte_t *ptep;
- /*
- * Huge pages are always in RAM for now, but
- * theoretically it needs to be checked.
- */
- ptep = huge_pte_offset(current->mm,
- addr & huge_page_mask(h));
- present = ptep && !huge_pte_none(huge_ptep_get(ptep));
- while (1) {
- *vec = present;
- vec++;
- addr += PAGE_SIZE;
- if (addr == end)
- return;
- /* check hugepage border */
- if (!(addr & ~huge_page_mask(h)))
- break;
- }
- }
+ /*
+ * Huge pages are always in RAM for now, but
+ * theoretically it needs to be checked.
+ */
+ present = pte && !huge_pte_none(huge_ptep_get(pte));
+ for (; addr != end; vec++, addr += PAGE_SIZE)
+ *vec = present;
+ cond_resched();
+ walk->private += (end - addr) >> PAGE_SHIFT;
#else
BUG();
#endif
+ return err;
}
/*
@@ -94,10 +83,11 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
return present;
}
-static void mincore_unmapped_range(struct vm_area_struct *vma,
- unsigned long addr, unsigned long end,
- unsigned char *vec)
+static int mincore_hole(unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
{
+ struct vm_area_struct *vma = walk->vma;
+ unsigned char *vec = walk->private;
unsigned long nr = (end - addr) >> PAGE_SHIFT;
int i;
@@ -111,110 +101,55 @@ static void mincore_unmapped_range(struct vm_area_struct *vma,
for (i = 0; i < nr; i++)
vec[i] = 0;
}
+ walk->private += nr;
+ return 0;
}
-static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
- unsigned long addr, unsigned long end,
- unsigned char *vec)
+static int mincore_pte(pte_t *pte, unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
{
- unsigned long next;
- spinlock_t *ptl;
- pte_t *ptep;
-
- ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- do {
- pte_t pte = *ptep;
- pgoff_t pgoff;
-
- next = addr + PAGE_SIZE;
- if (pte_none(pte))
- mincore_unmapped_range(vma, addr, next, vec);
- else if (pte_present(pte))
+ struct vm_area_struct *vma = walk->vma;
+ unsigned char *vec = walk->private;
+ pgoff_t pgoff;
+
+ if (pte_present(*pte))
+ *vec = 1;
+ else if (pte_file(*pte)) {
+ pgoff = pte_to_pgoff(*pte);
+ *vec = mincore_page(vma->vm_file->f_mapping, pgoff);
+ } else { /* pte is a swap entry */
+ swp_entry_t entry = pte_to_swp_entry(*pte);
+
+ if (is_migration_entry(entry)) {
+ /* migration entries are always uptodate */
*vec = 1;
- else if (pte_file(pte)) {
- pgoff = pte_to_pgoff(pte);
- *vec = mincore_page(vma->vm_file->f_mapping, pgoff);
- } else { /* pte is a swap entry */
- swp_entry_t entry = pte_to_swp_entry(pte);
-
- if (is_migration_entry(entry)) {
- /* migration entries are always uptodate */
- *vec = 1;
- } else {
+ } else {
#ifdef CONFIG_SWAP
- pgoff = entry.val;
- *vec = mincore_page(swap_address_space(entry),
- pgoff);
+ pgoff = entry.val;
+ *vec = mincore_page(swap_address_space(entry),
+ pgoff);
#else
- WARN_ON(1);
- *vec = 1;
+ WARN_ON(1);
+ *vec = 1;
#endif
- }
}
- vec++;
- } while (ptep++, addr = next, addr != end);
- pte_unmap_unlock(ptep - 1, ptl);
-}
-
-static void mincore_pmd_range(struct vm_area_struct *vma, pud_t *pud,
- unsigned long addr, unsigned long end,
- unsigned char *vec)
-{
- unsigned long next;
- pmd_t *pmd;
-
- pmd = pmd_offset(pud, addr);
- do {
- next = pmd_addr_end(addr, end);
- if (pmd_trans_huge(*pmd)) {
- if (mincore_huge_pmd(vma, pmd, addr, next, vec)) {
- vec += (next - addr) >> PAGE_SHIFT;
- continue;
- }
- /* fall through */
- }
- if (pmd_none_or_trans_huge_or_clear_bad(pmd))
- mincore_unmapped_range(vma, addr, next, vec);
- else
- mincore_pte_range(vma, pmd, addr, next, vec);
- vec += (next - addr) >> PAGE_SHIFT;
- } while (pmd++, addr = next, addr != end);
-}
-
-static void mincore_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
- unsigned long addr, unsigned long end,
- unsigned char *vec)
-{
- unsigned long next;
- pud_t *pud;
-
- pud = pud_offset(pgd, addr);
- do {
- next = pud_addr_end(addr, end);
- if (pud_none_or_clear_bad(pud))
- mincore_unmapped_range(vma, addr, next, vec);
- else
- mincore_pmd_range(vma, pud, addr, next, vec);
- vec += (next - addr) >> PAGE_SHIFT;
- } while (pud++, addr = next, addr != end);
+ }
+ walk->private++;
+ return 0;
}
-static void mincore_page_range(struct vm_area_struct *vma,
- unsigned long addr, unsigned long end,
- unsigned char *vec)
+static int mincore_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
{
- unsigned long next;
- pgd_t *pgd;
+ struct vm_area_struct *vma = walk->vma;
+ unsigned char *vec = walk->private;
- pgd = pgd_offset(vma->vm_mm, addr);
- do {
- next = pgd_addr_end(addr, end);
- if (pgd_none_or_clear_bad(pgd))
- mincore_unmapped_range(vma, addr, next, vec);
- else
- mincore_pud_range(vma, pgd, addr, next, vec);
- vec += (next - addr) >> PAGE_SHIFT;
- } while (pgd++, addr = next, addr != end);
+ if (mincore_huge_pmd(vma, pmd, addr, end, vec)) {
+ walk->private += (end - addr) >> PAGE_SHIFT;
+ /* don't call micore_pte() */
+ walk->skip = 1;
+ }
+ return 0;
}
/*
@@ -226,6 +161,7 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v
{
struct vm_area_struct *vma;
unsigned long end;
+ int err;
vma = find_vma(current->mm, addr);
if (!vma || addr < vma->vm_start)
@@ -233,12 +169,20 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v
end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
- if (is_vm_hugetlb_page(vma))
- mincore_hugetlb_page_range(vma, addr, end, vec);
+ struct mm_walk mincore_walk = {
+ .pmd_entry = mincore_pmd,
+ .pte_entry = mincore_pte,
+ .pte_hole = mincore_hole,
+ .hugetlb_entry = mincore_hugetlb,
+ .mm = vma->vm_mm,
+ .vma = vma,
+ .private = vec,
+ };
+ err = walk_page_vma(vma, &mincore_walk);
+ if (err < 0)
+ return err;
else
- mincore_page_range(vma, addr, end, vec);
-
- return (end - addr) >> PAGE_SHIFT;
+ return (end - addr) >> PAGE_SHIFT;
}
/*
--
1.9.3
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