diff options
Diffstat (limited to 'mm/swapfile.c')
| -rw-r--r-- | mm/swapfile.c | 32 |
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; } |