v2 - used mm->page_table_lock to fix up locking bug that
Mel pointed out. Also remove Acks since things
got changed significantly.
This adds code to explicitly detect and handle
pmd_trans_huge() pmds. It then passes HPAGE_SIZE units
in to the smap_pte_entry() function instead of PAGE_SIZE.
This means that using /proc/$pid/smaps now will no longer
cause THPs to be broken down in to small pages.
Signed-off-by: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
---
linux-2.6.git-dave/fs/proc/task_mmu.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff -puN fs/proc/task_mmu.c~teach-smaps_pte_range-about-thp-pmds fs/proc/task_mmu.c
--- linux-2.6.git/fs/proc/task_mmu.c~teach-smaps_pte_range-about-thp-pmds 2011-02-14 09:59:44.034590716 -0800
+++ linux-2.6.git-dave/fs/proc/task_mmu.c 2011-02-21 15:12:46.144181298 -0800
@@ -1,5 +1,6 @@
#include <linux/mm.h>
#include <linux/hugetlb.h>
+#include <linux/huge_mm.h>
#include <linux/mount.h>
#include <linux/seq_file.h>
#include <linux/highmem.h>
@@ -7,6 +8,7 @@
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/mempolicy.h>
+#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/swapops.h>
@@ -385,8 +387,25 @@ static int smaps_pte_range(pmd_t *pmd, u
pte_t *pte;
spinlock_t *ptl;
- split_huge_page_pmd(walk->mm, pmd);
-
+ spin_lock(&walk->mm->page_table_lock);
+ if (pmd_trans_huge(*pmd)) {
+ if (pmd_trans_splitting(*pmd)) {
+ spin_unlock(&walk->mm->page_table_lock);
+ wait_split_huge_page(vma->anon_vma, pmd);
+ } else {
+ smaps_pte_entry(*(pte_t *)pmd, addr,
+ HPAGE_PMD_SIZE, walk);
+ spin_unlock(&walk->mm->page_table_lock);
+ return 0;
+ }
+ } else {
+ spin_unlock(&walk->mm->page_table_lock);
+ }
+ /*
+ * The mmap_sem held all the way back in m_start() is what
+ * keeps khugepaged out of here and from collapsing things
+ * in here.
+ */
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
for (; addr != end; pte++, addr += PAGE_SIZE)
smaps_pte_entry(*pte, addr, PAGE_SIZE, walk);
diff -puN mm/migrate.c~teach-smaps_pte_range-about-thp-pmds mm/migrate.c
diff -puN mm/mincore.c~teach-smaps_pte_range-about-thp-pmds mm/mincore.c
diff -puN include/linux/mm.h~teach-smaps_pte_range-about-thp-pmds include/linux/mm.h
diff -puN mm/mempolicy.c~teach-smaps_pte_range-about-thp-pmds mm/mempolicy.c
_
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