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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-06-12 16:29:53 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-06-12 16:29:53 -0700 |
| commit | a568fa1c91d4f0e565345119d0b942cc7f74ca3d (patch) | |
| tree | 8d57522244da002e44b2f79cc2b376799630ba83 /mm/swap_state.c | |
| parent | 1a9c3d68d65f4b5ce32f7d67ccc730396e04cdd2 (diff) | |
| parent | c2853c8df57f49620d26f317d7d43347c29bfc2e (diff) | |
Merge branch 'akpm' (updates from Andrew Morton)
Merge misc fixes from Andrew Morton:
"Bunch of fixes and one little addition to math64.h"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (27 commits)
include/linux/math64.h: add div64_ul()
mm: memcontrol: fix lockless reclaim hierarchy iterator
frontswap: fix incorrect zeroing and allocation size for frontswap_map
kernel/audit_tree.c:audit_add_tree_rule(): protect `rule' from kill_rules()
mm: migration: add migrate_entry_wait_huge()
ocfs2: add missing lockres put in dlm_mig_lockres_handler
mm/page_alloc.c: fix watermark check in __zone_watermark_ok()
drivers/misc/sgi-gru/grufile.c: fix info leak in gru_get_config_info()
aio: fix io_destroy() regression by using call_rcu()
rtc-at91rm9200: use shadow IMR on at91sam9x5
rtc-at91rm9200: add shadow interrupt mask
rtc-at91rm9200: refactor interrupt-register handling
rtc-at91rm9200: add configuration support
rtc-at91rm9200: add match-table compile guard
fs/ocfs2/namei.c: remove unecessary ERROR when removing non-empty directory
swap: avoid read_swap_cache_async() race to deadlock while waiting on discard I/O completion
drivers/rtc/rtc-twl.c: fix missing device_init_wakeup() when booted with device tree
cciss: fix broken mutex usage in ioctl
audit: wait_for_auditd() should use TASK_UNINTERRUPTIBLE
drivers/rtc/rtc-cmos.c: fix accidentally enabling rtc channel
...
Diffstat (limited to 'mm/swap_state.c')
| -rw-r--r-- | mm/swap_state.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/mm/swap_state.c b/mm/swap_state.c index b3d40dcf3624..f24ab0dff554 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -336,8 +336,24 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, * Swap entry may have been freed since our caller observed it. */ err = swapcache_prepare(entry); - if (err == -EEXIST) { /* seems racy */ + if (err == -EEXIST) { radix_tree_preload_end(); + /* + * We might race against get_swap_page() and stumble + * across a SWAP_HAS_CACHE swap_map entry whose page + * has not been brought into the swapcache yet, while + * the other end is scheduled away waiting on discard + * I/O completion at scan_swap_map(). + * + * In order to avoid turning this transitory state + * into a permanent loop around this -EEXIST case + * if !CONFIG_PREEMPT and the I/O completion happens + * to be waiting on the CPU waitqueue where we are now + * busy looping, we just conditionally invoke the + * scheduler here, if there are some more important + * tasks to run. + */ + cond_resched(); continue; } if (err) { /* swp entry is obsolete ? */ |