The prototype of the new swapoff (without the quadratic complexity)
presently ignores the frontswap case. Pass the count of
pages_to_unuse down the page table walks in try_to_unuse(),
and return from the walk when the desired number of pages
has been swapped back in.
Signed-off-by: Kelley Nielsen <kelleynnn@xxxxxxxxx>
---
Changes since v6:
- In try_to_unuse(), copy pages_to_unuse to local fs_pages_to_unuse
and pass by reference (instead of value) down the page table walk
- create #define FRONTSWAP_PAGES_UNUSED to pass special code
back up the chain from unuse_pte_range()
- Test for this return code in try_to_unuse() and exit before
orphans cleanup and retries
- In unuse_pte_range, move decrement of frontswap pages count
next to call to delete_from_swap_cache(), so that it happens
on every unused swap slot instead of every pte unmap
- Remove unnecessary goto after call to unuse_mm() in try_to_unuse()
- Remove blank line in shmem.c/shmem_unuse_inode()
---
mm/swapfile.c | 60 +++++++++++++++++++++++++++++++++++++++++------------------
1 file changed, 42 insertions(+), 18 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 79c47b6..e4f5289 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1144,9 +1144,11 @@ out_nolock:
return ret;
}
+#define FRONTSWAP_PAGES_UNUSED 2
static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end,
- unsigned int type)
+ unsigned int type,
+ unsigned long *fs_pages_to_unuse)
{
struct page *page;
swp_entry_t entry;
@@ -1169,6 +1171,8 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
continue;
if (found_type != type)
continue;
+ if ((*fs_pages_to_unuse > 0) && (!frontswap_test(si, offset)))
+ continue;
swap_map = &si->swap_map[offset];
if (!swap_count(*swap_map))
@@ -1205,11 +1209,18 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
if (PageSwapCache(page) && (swap_count(*swap_map) == 0)) {
wait_on_page_writeback(page);
delete_from_swap_cache(page);
+ if (*fs_pages_to_unuse > 0) {
+ (*fs_pages_to_unuse)--;
+ if (*fs_pages_to_unuse == 0)
+ ret = FRONTSWAP_PAGES_UNUSED;
+ }
}
SetPageDirty(page);
unlock_page(page);
page_cache_release(page);
+ if (ret == FRONTSWAP_PAGES_UNUSED)
+ goto out;
try_next:
pte = pte_offset_map(pmd, addr);
} while (pte++, addr += PAGE_SIZE, addr != end);
@@ -1220,7 +1231,8 @@ out:
static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
unsigned long addr, unsigned long end,
- unsigned int type)
+ unsigned int type,
+ unsigned long *fs_pages_to_unuse)
{
pmd_t *pmd;
unsigned long next;
@@ -1231,8 +1243,9 @@ static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
next = pmd_addr_end(addr, end);
if (pmd_none_or_trans_huge_or_clear_bad(pmd))
continue;
- ret = unuse_pte_range(vma, pmd, addr, next, type);
- if (ret < 0)
+ ret = unuse_pte_range(vma, pmd, addr, next, type,
+ fs_pages_to_unuse);
+ if (ret < 0 || ret == 2)
return ret;
} while (pmd++, addr = next, addr != end);
return 0;
@@ -1240,7 +1253,8 @@ static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
unsigned long addr, unsigned long end,
- unsigned int type)
+ unsigned int type,
+ unsigned long *fs_pages_to_unuse)
{
pud_t *pud;
unsigned long next;
@@ -1251,14 +1265,16 @@ static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
- ret = unuse_pmd_range(vma, pud, addr, next, type);
- if (ret < 0)
+ ret = unuse_pmd_range(vma, pud, addr, next, type,
+ fs_pages_to_unuse);
+ if (ret < 0 || ret == 2)
return ret;
} while (pud++, addr = next, addr != end);
return 0;
}
-static int unuse_vma(struct vm_area_struct *vma, unsigned int type)
+static int unuse_vma(struct vm_area_struct *vma, unsigned int type,
+ unsigned long *fs_pages_to_unuse)
{
pgd_t *pgd;
unsigned long addr, end, next;
@@ -1272,14 +1288,16 @@ static int unuse_vma(struct vm_area_struct *vma, unsigned int type)
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
- ret = unuse_pud_range(vma, pgd, addr, next, type);
- if (ret < 0)
+ ret = unuse_pud_range(vma, pgd, addr, next, type,
+ fs_pages_to_unuse);
+ if (ret < 0 || ret == 2)
return ret;
} while (pgd++, addr = next, addr != end);
return 0;
}
-static int unuse_mm(struct mm_struct *mm, unsigned int type)
+static int unuse_mm(struct mm_struct *mm, unsigned int type,
+ unsigned long *fs_pages_to_unuse)
{
struct vm_area_struct *vma;
int ret = 0;
@@ -1287,7 +1305,7 @@ static int unuse_mm(struct mm_struct *mm, unsigned int type)
down_read(&mm->mmap_sem);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (vma->anon_vma) {
- ret = unuse_vma(vma, type);
+ ret = unuse_vma(vma, type, fs_pages_to_unuse);
if (ret)
break;
}
@@ -1342,7 +1360,6 @@ static unsigned int find_next_to_unuse(struct swap_info_struct *si,
return i;
}
-/* TODO: frontswap */
#define MAX_RETRIES 3
int try_to_unuse(unsigned int type, bool frontswap,
unsigned long pages_to_unuse)
@@ -1354,10 +1371,14 @@ int try_to_unuse(unsigned int type, bool frontswap,
struct swap_info_struct *si = swap_info[type];
struct page *page;
swp_entry_t entry;
+ unsigned long fs_pages_to_unuse = 0;
unsigned int i = 0;
unsigned int oldi = 0;
int retries = 0;
+ if (frontswap)
+ fs_pages_to_unuse = pages_to_unuse;
+
retry:
retval = shmem_unuse(type);
if (retval)
@@ -1381,9 +1402,7 @@ retry:
mmput(prev_mm);
prev_mm = mm;
- retval = unuse_mm(mm, type);
- if (retval)
- goto out_put;
+ retval = unuse_mm(mm, type, &fs_pages_to_unuse);
/*
* Make sure that we aren't completely killing
@@ -1396,8 +1415,13 @@ retry:
out_put:
mmput(prev_mm);
- if (retval)
+ if (retval < 0)
+ goto out;
+ if (retval == FRONTSWAP_PAGES_UNUSED) {
+ retval = 0;
goto out;
+ }
+
while ((i = find_next_to_unuse(si, i, frontswap)) != 0) {
/*
* under global memory pressure, swap entries
@@ -1410,7 +1434,7 @@ out_put:
*/
if (i < oldi) {
retries++;
- if (retries > MAX_RETRIES) {
+ if ((retries > MAX_RETRIES) || frontswap) {
retval = -EBUSY;
goto out;
}
--
1.8.3.2
--
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