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mm: numa: Sanitize task_numa_fault() callsites
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commit c61109e upstream.

There are three callers of task_numa_fault():

 - do_huge_pmd_numa_page():
     Accounts against the current node, not the node where the
     page resides, unless we migrated, in which case it accounts
     against the node we migrated to.

 - do_numa_page():
     Accounts against the current node, not the node where the
     page resides, unless we migrated, in which case it accounts
     against the node we migrated to.

 - do_pmd_numa_page():
     Accounts not at all when the page isn't migrated, otherwise
     accounts against the node we migrated towards.

This seems wrong to me; all three sites should have the same
sementaics, furthermore we should accounts against where the page
really is, we already know where the task is.

So modify all three sites to always account; we did after all receive
the fault; and always account to where the page is after migration,
regardless of success.

They all still differ on when they clear the PTE/PMD; ideally that
would get sorted too.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-8-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@gregkh
Mel Gorman authored and gregkh committed Nov 13, 2013
1 parent 93a21ff commit b5af02f
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Showing 2 changed files with 34 additions and 44 deletions.
25 changes: 13 additions & 12 deletions mm/huge_memory.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1293,18 +1293,19 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
struct anon_vma *anon_vma = NULL;
struct page *page;
unsigned long haddr = addr & HPAGE_PMD_MASK;
int page_nid = -1, this_nid = numa_node_id();
int target_nid;
int current_nid = -1;
bool migrated, page_locked;
bool page_locked;
bool migrated = false;

spin_lock(&mm->page_table_lock);
if (unlikely(!pmd_same(pmd, *pmdp)))
goto out_unlock;

page = pmd_page(pmd);
current_nid = page_to_nid(page);
page_nid = page_to_nid(page);
count_vm_numa_event(NUMA_HINT_FAULTS);
if (current_nid == numa_node_id())
if (page_nid == this_nid)
count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);

/*
Expand Down Expand Up @@ -1347,19 +1348,18 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
spin_unlock(&mm->page_table_lock);
migrated = migrate_misplaced_transhuge_page(mm, vma,
pmdp, pmd, addr, page, target_nid);
if (!migrated)
if (migrated)
page_nid = target_nid;
else
goto check_same;

task_numa_fault(target_nid, HPAGE_PMD_NR, true);
if (anon_vma)
page_unlock_anon_vma_read(anon_vma);
return 0;
goto out;

check_same:
spin_lock(&mm->page_table_lock);
if (unlikely(!pmd_same(pmd, *pmdp))) {
/* Someone else took our fault */
current_nid = -1;
page_nid = -1;
goto out_unlock;
}
clear_pmdnuma:
Expand All @@ -1374,8 +1374,9 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
if (anon_vma)
page_unlock_anon_vma_read(anon_vma);

if (current_nid != -1)
task_numa_fault(current_nid, HPAGE_PMD_NR, false);
if (page_nid != -1)
task_numa_fault(page_nid, HPAGE_PMD_NR, migrated);

return 0;
}

Expand Down
53 changes: 21 additions & 32 deletions mm/memory.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3532,12 +3532,12 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
}

int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
unsigned long addr, int current_nid)
unsigned long addr, int page_nid)
{
get_page(page);

count_vm_numa_event(NUMA_HINT_FAULTS);
if (current_nid == numa_node_id())
if (page_nid == numa_node_id())
count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);

return mpol_misplaced(page, vma, addr);
Expand All @@ -3548,7 +3548,7 @@ int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
{
struct page *page = NULL;
spinlock_t *ptl;
int current_nid = -1;
int page_nid = -1;
int target_nid;
bool migrated = false;

Expand Down Expand Up @@ -3578,27 +3578,22 @@ int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
return 0;
}

current_nid = page_to_nid(page);
target_nid = numa_migrate_prep(page, vma, addr, current_nid);
page_nid = page_to_nid(page);
target_nid = numa_migrate_prep(page, vma, addr, page_nid);
pte_unmap_unlock(ptep, ptl);
if (target_nid == -1) {
/*
* Account for the fault against the current node if it not
* being replaced regardless of where the page is located.
*/
current_nid = numa_node_id();
put_page(page);
goto out;
}

/* Migrate to the requested node */
migrated = migrate_misplaced_page(page, target_nid);
if (migrated)
current_nid = target_nid;
page_nid = target_nid;

out:
if (current_nid != -1)
task_numa_fault(current_nid, 1, migrated);
if (page_nid != -1)
task_numa_fault(page_nid, 1, migrated);
return 0;
}

Expand All @@ -3613,7 +3608,6 @@ static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long offset;
spinlock_t *ptl;
bool numa = false;
int local_nid = numa_node_id();

spin_lock(&mm->page_table_lock);
pmd = *pmdp;
Expand All @@ -3636,9 +3630,10 @@ static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
for (addr = _addr + offset; addr < _addr + PMD_SIZE; pte++, addr += PAGE_SIZE) {
pte_t pteval = *pte;
struct page *page;
int curr_nid = local_nid;
int page_nid = -1;
int target_nid;
bool migrated;
bool migrated = false;

if (!pte_present(pteval))
continue;
if (!pte_numa(pteval))
Expand All @@ -3660,25 +3655,19 @@ static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
if (unlikely(page_mapcount(page) != 1))
continue;

/*
* Note that the NUMA fault is later accounted to either
* the node that is currently running or where the page is
* migrated to.
*/
curr_nid = local_nid;
target_nid = numa_migrate_prep(page, vma, addr,
page_to_nid(page));
if (target_nid == -1) {
page_nid = page_to_nid(page);
target_nid = numa_migrate_prep(page, vma, addr, page_nid);
pte_unmap_unlock(pte, ptl);
if (target_nid != -1) {
migrated = migrate_misplaced_page(page, target_nid);
if (migrated)
page_nid = target_nid;
} else {
put_page(page);
continue;
}

/* Migrate to the requested node */
pte_unmap_unlock(pte, ptl);
migrated = migrate_misplaced_page(page, target_nid);
if (migrated)
curr_nid = target_nid;
task_numa_fault(curr_nid, 1, migrated);
if (page_nid != -1)
task_numa_fault(page_nid, 1, migrated);

pte = pte_offset_map_lock(mm, pmdp, addr, &ptl);
}
Expand Down

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