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authorDave Airlie <airlied@redhat.com>2013-06-27 20:40:44 +1000
committerDave Airlie <airlied@redhat.com>2013-06-27 20:40:44 +1000
commit4300a0f8bdcce5a03b88bfa16fc9827e15c52dc4 (patch)
treedea0276d7d0a12147f04ddbef9121e32e903c5ca /mm/swap_state.c
parent160954b7bca43da7cd3cfbce310e6df919a8216e (diff)
parent9e895ace5d82df8929b16f58e9f515f6d54ab82d (diff)
Merge tag 'v3.10-rc7' into drm-next
Linux 3.10-rc7 The sdvo lvds fix in this -fixes pull commit c3456fb3e4712d0448592af3c5d644c9472cd3c1 Author: Daniel Vetter <daniel.vetter@ffwll.ch> Date: Mon Jun 10 09:47:58 2013 +0200 drm/i915: prefer VBT modes for SVDO-LVDS over EDID has a silent functional conflict with commit 990256aec2f10800595dddf4d1c3441fcd6b2616 Author: Ville Syrjälä <ville.syrjala@linux.intel.com> Date: Fri May 31 12:17:07 2013 +0000 drm: Add probed modes in probe order in drm-next. W simply need to add the vbt modes before edid modes, i.e. the other way round than now. Conflicts: drivers/gpu/drm/drm_prime.c drivers/gpu/drm/i915/intel_sdvo.c
Diffstat (limited to 'mm/swap_state.c')
-rw-r--r--mm/swap_state.c18
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if (err) { /* swp entry is obsolete ? */