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| author | James Bottomley <JBottomley@Parallels.com> | 2013-06-26 23:08:22 -0700 |
|---|---|---|
| committer | James Bottomley <JBottomley@Parallels.com> | 2013-06-26 23:08:22 -0700 |
| commit | a9e94ec3504ead4b87a929bc57f5aa99a6590437 (patch) | |
| tree | b6e7aaec0e844dc066e93296a85e5769542ef525 /mm/swap_state.c | |
| parent | 36a279686bc02d340eb213a9f2a0b67e50de64b4 (diff) | |
| parent | 2884d4230867c8a46cf701214051e923301e7429 (diff) | |
Merge tag 'fcoe1' into fixes
This patch fixes a critical bug that was introduced in 3.9
related to VLAN tagging FCoE frames.
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 b3d40dcf362..f24ab0dff55 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 + */ + cond_resched(); continue; } if (err) { /* swp entry is obsolete ? */ |