The patch titled
fix rcu_read_lock() in page migraton
has been added to the -mm tree. Its filename is
fix-rcu_read_lock-in-page-migraton.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: fix rcu_read_lock() in page migraton
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
In migration fallback path, write_page() or lock_page() will be called.
This causes sleep with holding rcu_read_lock().
For avoding that, just do rcu_lock if the page is Anon.(this is enough.)
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Acked-by: Christoph Lameter <clameter@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 11 +++++++++--
1 files changed, 9 insertions(+), 2 deletions(-)
diff -puN mm/migrate.c~fix-rcu_read_lock-in-page-migraton mm/migrate.c
--- a/mm/migrate.c~fix-rcu_read_lock-in-page-migraton
+++ a/mm/migrate.c
@@ -611,6 +611,7 @@ static int unmap_and_move(new_page_t get
int rc = 0;
int *result = NULL;
struct page *newpage = get_new_page(page, private, &result);
+ int rcu_locked = 0;
if (!newpage)
return -ENOMEM;
@@ -636,8 +637,13 @@ static int unmap_and_move(new_page_t get
* we cannot notice that anon_vma is freed while we migrates a page.
* This rcu_read_lock() delays freeing anon_vma pointer until the end
* of migration. File cache pages are no problem because of page_lock()
+ * File Caches may use write_page() or lock_page() in migration, then,
+ * just care Anon page here.
*/
- rcu_read_lock();
+ if (PageAnon(page)) {
+ rcu_read_lock();
+ rcu_locked = 1;
+ }
/*
* This is a corner case handling.
* When a new swap-cache is read into, it is linked to LRU
@@ -656,7 +662,8 @@ static int unmap_and_move(new_page_t get
if (rc)
remove_migration_ptes(page, page);
rcu_unlock:
- rcu_read_unlock();
+ if (rcu_locked)
+ rcu_read_unlock();
unlock:
_
Patches currently in -mm which might be from kamezawa.hiroyu@xxxxxxxxxxxxxx are
fix-rcu_read_lock-in-page-migraton.patch
sparsemem-clean-up-spelling-error-in-comments.patch
sparsemem-record-when-a-section-has-a-valid-mem_map.patch
generic-virtual-memmap-support-for-sparsemem.patch
generic-virtual-memmap-support-for-sparsemem-fix.patch
x86_64-sparsemem_vmemmap-2m-page-size-support.patch
x86_64-sparsemem_vmemmap-2m-page-size-support-ensure-end-of-section-memmap-is-initialised.patch
x86_64-sparsemem_vmemmap-vmemmap-x86_64-convert-to-new-helper-based-initialisation.patch
ia64-sparsemem_vmemmap-16k-page-size-support.patch
ia64-sparsemem_vmemmap-16k-page-size-support-convert-to-new-helper-based-initialisation.patch
sparc64-sparsemem_vmemmap-support.patch
sparc64-sparsemem_vmemmap-support-vmemmap-convert-to-new-config-options.patch
ppc64-sparsemem_vmemmap-support.patch
ppc64-sparsemem_vmemmap-support-convert-to-new-config-options.patch
memoryless-nodes-generic-management-of-nodemasks-for-various-purposes.patch
memoryless-nodes-introduce-mask-of-nodes-with-memory.patch
memoryless-nodes-introduce-mask-of-nodes-with-memory-fix.patch
memoryless-nodes-fix-interleave-behavior-for-memoryless-nodes.patch
memoryless-nodes-oom-use-n_high_memory-map-instead-of-constructing-one-on-the-fly.patch
memoryless-nodes-no-need-for-kswapd.patch
memoryless-nodes-slab-support.patch
memoryless-nodes-slub-support.patch
memoryless-nodes-uncached-allocator-updates.patch
memoryless-nodes-allow-profiling-data-to-fall-back-to-other-nodes.patch
memoryless-nodes-update-memory-policy-and-page-migration.patch
memoryless-nodes-add-n_cpu-node-state.patch
memoryless-nodes-drop-one-memoryless-node-boot-warning.patch
memoryless-nodes-fix-gfp_thisnode-behavior.patch
memoryless-nodes-use-n_high_memory-for-cpusets.patch
flush-cache-before-installing-new-page-at-migraton.patch
flush-icache-before-set_pte-on-ia64-flush-icache-at-set_pte.patch
flush-icache-before-set_pte-on-ia64-flush-icache-at-set_pte-fix.patch
flush-icache-before-set_pte-on-ia64-flush-icache-at-set_pte-fix-update.patch
memory-unplug-v7-memory-hotplug-cleanup.patch
memory-unplug-v7-page-isolation.patch
memory-unplug-v7-page-offline.patch
memory-unplug-v7-ia64-interface.patch
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