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Subject[RFC v2 27/43] mm: shmem: when inserting, handle pages already charged to a memcg
Date
If shmem_insert_page() is called to insert a page that was preserved
using PKRAM on the current boot (i.e. preserved page is restored without
an intervening kexec boot), the page will still be charged to a memory
cgroup because it is never freed. Don't try to charge it again.

Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
---
mm/shmem.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 8dfe80aeee97..44cc158ab34d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -671,7 +671,7 @@ static inline bool is_huge_enabled(struct shmem_sb_info *sbinfo)
static int shmem_add_to_page_cache(struct page *page,
struct address_space *mapping,
pgoff_t index, void *expected, gfp_t gfp,
- struct mm_struct *charge_mm)
+ struct mm_struct *charge_mm, bool skipcharge)
{
XA_STATE_ORDER(xas, &mapping->i_pages, index, compound_order(page));
unsigned long i = 0;
@@ -688,7 +688,7 @@ static int shmem_add_to_page_cache(struct page *page,
page->mapping = mapping;
page->index = index;

- if (!PageSwapCache(page)) {
+ if (!skipcharge && !PageSwapCache(page)) {
error = mem_cgroup_charge(page, charge_mm, gfp);
if (error) {
if (PageTransHuge(page)) {
@@ -770,6 +770,7 @@ int shmem_insert_page(struct mm_struct *mm, struct inode *inode, pgoff_t index,
int nr;
pgoff_t hindex = index;
bool on_lru = PageLRU(page);
+ bool ischarged = page_memcg(page) ? true : false;

if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
return -EFBIG;
@@ -809,7 +810,8 @@ int shmem_insert_page(struct mm_struct *mm, struct inode *inode, pgoff_t index,
__SetPageReferenced(page);

err = shmem_add_to_page_cache(page, mapping, hindex,
- NULL, gfp & GFP_RECLAIM_MASK, mm);
+ NULL, gfp & GFP_RECLAIM_MASK,
+ mm, ischarged);
if (err)
goto out_unlock;

@@ -1829,7 +1831,7 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index,

error = shmem_add_to_page_cache(page, mapping, index,
swp_to_radix_entry(swap), gfp,
- charge_mm);
+ charge_mm, false);
if (error)
goto failed;

@@ -2009,7 +2011,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,

error = shmem_add_to_page_cache(page, mapping, hindex,
NULL, gfp & GFP_RECLAIM_MASK,
- charge_mm);
+ charge_mm, false);
if (error)
goto unacct;
lru_cache_add(page);
@@ -2500,7 +2502,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
goto out_release;

ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL,
- gfp & GFP_RECLAIM_MASK, dst_mm);
+ gfp & GFP_RECLAIM_MASK, dst_mm, false);
if (ret)
goto out_release;

--
1.8.3.1
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