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authorDavid S. Miller <davem@davemloft.net>2019-04-25 23:52:29 -0400
committerDavid S. Miller <davem@davemloft.net>2019-04-25 23:52:29 -0400
commit8b4483658364f05b2e32845c8f445cdfd9452286 (patch)
tree4734ef83378b1e90475ec4776ac72dfe16a7249b /mm/swapfile.c
parentc049d56eb219661c9ae48d596c3e633973f89d1f (diff)
parentcd8dead0c39457e58ec1d36db93aedca811d48f1 (diff)
downloadlinux-8b4483658364f05b2e32845c8f445cdfd9452286.tar.bz2
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Two easy cases of overlapping changes. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'mm/swapfile.c')
-rw-r--r--mm/swapfile.c32
1 files changed, 17 insertions, 15 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 2b8d9c3fbb47..cf63b5f01adf 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2023,7 +2023,6 @@ static unsigned int find_next_to_unuse(struct swap_info_struct *si,
* If the boolean frontswap is true, only unuse pages_to_unuse pages;
* pages_to_unuse==0 means all pages; ignored if frontswap is false
*/
-#define SWAP_UNUSE_MAX_TRIES 3
int try_to_unuse(unsigned int type, bool frontswap,
unsigned long pages_to_unuse)
{
@@ -2035,7 +2034,6 @@ int try_to_unuse(unsigned int type, bool frontswap,
struct page *page;
swp_entry_t entry;
unsigned int i;
- int retries = 0;
if (!si->inuse_pages)
return 0;
@@ -2053,11 +2051,9 @@ retry:
spin_lock(&mmlist_lock);
p = &init_mm.mmlist;
- while ((p = p->next) != &init_mm.mmlist) {
- if (signal_pending(current)) {
- retval = -EINTR;
- break;
- }
+ while (si->inuse_pages &&
+ !signal_pending(current) &&
+ (p = p->next) != &init_mm.mmlist) {
mm = list_entry(p, struct mm_struct, mmlist);
if (!mmget_not_zero(mm))
@@ -2084,7 +2080,9 @@ retry:
mmput(prev_mm);
i = 0;
- while ((i = find_next_to_unuse(si, i, frontswap)) != 0) {
+ while (si->inuse_pages &&
+ !signal_pending(current) &&
+ (i = find_next_to_unuse(si, i, frontswap)) != 0) {
entry = swp_entry(type, i);
page = find_get_page(swap_address_space(entry), i);
@@ -2117,14 +2115,18 @@ retry:
* If yes, we would need to do retry the unuse logic again.
* Under global memory pressure, swap entries can be reinserted back
* into process space after the mmlist loop above passes over them.
- * Its not worth continuosuly retrying to unuse the swap in this case.
- * So we try SWAP_UNUSE_MAX_TRIES times.
+ *
+ * Limit the number of retries? No: when mmget_not_zero() above fails,
+ * that mm is likely to be freeing swap from exit_mmap(), which proceeds
+ * at its own independent pace; and even shmem_writepage() could have
+ * been preempted after get_swap_page(), temporarily hiding that swap.
+ * It's easy and robust (though cpu-intensive) just to keep retrying.
*/
- if (++retries >= SWAP_UNUSE_MAX_TRIES)
- retval = -EBUSY;
- else if (si->inuse_pages)
- goto retry;
-
+ if (si->inuse_pages) {
+ if (!signal_pending(current))
+ goto retry;
+ retval = -EINTR;
+ }
out:
return (retval == FRONTSWAP_PAGES_UNUSED) ? 0 : retval;
}