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author | Wolfgang Wiedmeyer <wolfgit@wiedmeyer.de> | 2015-10-22 21:26:58 +0200 |
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committer | Wolfgang Wiedmeyer <wolfgit@wiedmeyer.de> | 2015-10-22 21:26:58 +0200 |
commit | 786208aedd8f75b0720e36b2ca66b3a411417301 (patch) | |
tree | e6e902ab383ca94842c8691a9e28e1a6aefc5695 /mm/swap_state.c | |
parent | b99374450c03bf5081b88995d91d34fb9b2fd040 (diff) | |
download | kernel_samsung_smdk4412-786208aedd8f75b0720e36b2ca66b3a411417301.zip kernel_samsung_smdk4412-786208aedd8f75b0720e36b2ca66b3a411417301.tar.gz kernel_samsung_smdk4412-786208aedd8f75b0720e36b2ca66b3a411417301.tar.bz2 |
merged 3.0.101 tag
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 10e9198..43b957e 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -315,8 +315,24 @@ 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 + */ + cond_resched(); continue; } if (err) { /* swp entry is obsolete ? */ |