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Subject[patch 05/10] emm: Remove tlb pointer from the parameters of unmap vmas
We no longer abort unmapping in unmap vmas because we can reschedule while
unmapping since we are holding a semaphore. This would allow moving more
of the tlb flusing into unmap_vmas reducing code in various places.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
include/linux/mm.h | 3 +--
mm/memory.c | 43 +++++++++++++++++--------------------------
mm/mmap.c | 18 +++---------------
3 files changed, 21 insertions(+), 43 deletions(-)
Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h 2008-04-01 13:02:41.374608387 -0700
+++ linux-2.6/include/linux/mm.h 2008-04-01 13:02:43.898651546 -0700
@@ -723,8 +723,7 @@ struct zap_details {
struct page *vm_normal_page(struct vm_area_struct *, unsigned long, pte_t);
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
unsigned long size, struct zap_details *);
-unsigned long unmap_vmas(struct mmu_gather **tlb,
- struct vm_area_struct *start_vma, unsigned long start_addr,
+unsigned long unmap_vmas(struct vm_area_struct *start_vma, unsigned long start_addr,
unsigned long end_addr, unsigned long *nr_accounted,
struct zap_details *);

Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c 2008-04-01 13:02:41.378608315 -0700
+++ linux-2.6/mm/memory.c 2008-04-01 13:02:43.902651345 -0700
@@ -806,7 +806,6 @@ static unsigned long unmap_page_range(st

/**
* unmap_vmas - unmap a range of memory covered by a list of vma's
- * @tlbp: address of the caller's struct mmu_gather
* @vma: the starting vma
* @start_addr: virtual address at which to start unmapping
* @end_addr: virtual address at which to end unmapping
@@ -818,20 +817,13 @@ static unsigned long unmap_page_range(st
* Unmap all pages in the vma list.
*
* We aim to not hold locks for too long (for scheduling latency reasons).
- * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
- * return the ending mmu_gather to the caller.
+ * So zap pages in ZAP_BLOCK_SIZE bytecounts.
*
* Only addresses between `start' and `end' will be unmapped.
*
* The VMA list must be sorted in ascending virtual address order.
- *
- * unmap_vmas() assumes that the caller will flush the whole unmapped address
- * range after unmap_vmas() returns. So the only responsibility here is to
- * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
- * drops the lock and schedules.
*/
-unsigned long unmap_vmas(struct mmu_gather **tlbp,
- struct vm_area_struct *vma, unsigned long start_addr,
+unsigned long unmap_vmas(struct vm_area_struct *vma, unsigned long start_addr,
unsigned long end_addr, unsigned long *nr_accounted,
struct zap_details *details)
{
@@ -839,7 +831,15 @@ unsigned long unmap_vmas(struct mmu_gath
unsigned long tlb_start = 0; /* For tlb_finish_mmu */
int tlb_start_valid = 0;
unsigned long start = start_addr;
- int fullmm = (*tlbp)->fullmm;
+ int fullmm;
+ struct mmu_gather *tlb;
+ struct mm_struct *mm = vma->vm_mm;
+
+ emm_notify(mm, emm_invalidate_start, start_addr, end_addr);
+ lru_add_drain();
+ tlb = tlb_gather_mmu(mm, 0);
+ update_hiwater_rss(mm);
+ fullmm = tlb->fullmm;

for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
unsigned long end;
@@ -866,7 +866,7 @@ unsigned long unmap_vmas(struct mmu_gath
(HPAGE_SIZE / PAGE_SIZE);
start = end;
} else
- start = unmap_page_range(*tlbp, vma,
+ start = unmap_page_range(tlb, vma,
start, end, &zap_work, details);

if (zap_work > 0) {
@@ -874,13 +874,15 @@ unsigned long unmap_vmas(struct mmu_gath
break;
}

- tlb_finish_mmu(*tlbp, tlb_start, start);
+ tlb_finish_mmu(tlb, tlb_start, start);
cond_resched();
- *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
+ tlb = tlb_gather_mmu(vma->vm_mm, fullmm);
tlb_start_valid = 0;
zap_work = ZAP_BLOCK_SIZE;
}
}
+ tlb_finish_mmu(tlb, start_addr, end_addr);
+ emm_notify(mm, emm_invalidate_end, start_addr, end_addr);
return start; /* which is now the end (or restart) address */
}

@@ -894,21 +896,10 @@ unsigned long unmap_vmas(struct mmu_gath
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
unsigned long size, struct zap_details *details)
{
- struct mm_struct *mm = vma->vm_mm;
- struct mmu_gather *tlb;
unsigned long end = address + size;
unsigned long nr_accounted = 0;

- emm_notify(mm, emm_invalidate_start, address, end);
- lru_add_drain();
- tlb = tlb_gather_mmu(mm, 0);
- update_hiwater_rss(mm);
-
- end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
- if (tlb)
- tlb_finish_mmu(tlb, address, end);
- emm_notify(mm, emm_invalidate_end, address, end);
- return end;
+ return unmap_vmas(vma, address, end, &nr_accounted, details);
}

/*
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c 2008-04-01 13:02:41.378608315 -0700
+++ linux-2.6/mm/mmap.c 2008-04-01 13:03:19.627259624 -0700
@@ -1741,19 +1741,12 @@ static void unmap_region(struct mm_struc
unsigned long start, unsigned long end)
{
struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
- struct mmu_gather *tlb;
unsigned long nr_accounted = 0;

- emm_notify(mm, emm_invalidate_start, start, end);
- lru_add_drain();
- tlb = tlb_gather_mmu(mm, 0);
- update_hiwater_rss(mm);
- unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
+ unmap_vmas(vma, start, end, &nr_accounted, NULL);
vm_unacct_memory(nr_accounted);
- tlb_finish_mmu(tlb, start, end);
free_pgtables(vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
next? next->vm_start: 0);
- emm_notify(mm, emm_invalidate_end, start, end);
}

/*
@@ -2033,7 +2026,6 @@ EXPORT_SYMBOL(do_brk);
/* Release all mmaps. */
void exit_mmap(struct mm_struct *mm)
{
- struct mmu_gather *tlb;
struct vm_area_struct *vma = mm->mmap;
unsigned long nr_accounted = 0;
unsigned long end;
@@ -2041,15 +2033,11 @@ void exit_mmap(struct mm_struct *mm)
/* mm's last user has gone, and its about to be pulled down */
arch_exit_mmap(mm);
emm_notify(mm, emm_release, 0, TASK_SIZE);
-
lru_add_drain();
flush_cache_mm(mm);
- tlb = tlb_gather_mmu(mm, 1);
- /* Don't update_hiwater_rss(mm) here, do_exit already did */
- /* Use -1 here to ensure all VMAs in the mm are unmapped */
- end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
+
+ end = unmap_vmas(vma, 0, -1, &nr_accounted, NULL);
vm_unacct_memory(nr_accounted);
- tlb_finish_mmu(tlb, 0, end);
free_pgtables(vma, FIRST_USER_ADDRESS, 0);

/*
--


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