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authorZqiang <qiang1.zhang@intel.com>2023-04-12 22:31:27 +0800
committerPaul E. McKenney <paulmck@kernel.org>2023-05-09 17:26:21 -0700
commit60888b77a06ea16665e4df980bb86b418253e268 (patch)
tree7afe5fc6bdac65bb933b8392689cead882d1664b /kernel/rcu
parent021a5ff8474379cd6c23e9b0e97aa27e5ff66a8b (diff)
rcu/kvfree: Make fill page cache start from krcp->nr_bkv_objs
When the fill_page_cache_func() function is invoked, it assumes that the cache of pages is completely empty. However, there can be some time between triggering execution of this function and its actual invocation. During this time, kfree_rcu_work() might run, and might fill in part or all of this cache of pages, thus invalidating the fill_page_cache_func() function's assumption. This will not overfill the cache because put_cached_bnode() will reject the extra page. However, it will result in a needless allocation and freeing of one extra page, which might not be helpful under lowish-memory conditions. This commit therefore causes the fill_page_cache_func() to explicitly account for pages that have been placed into the cache shortly before it starts running. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 18f592bf6dc6..98f2e833e217 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3201,7 +3201,7 @@ static void fill_page_cache_func(struct work_struct *work)
nr_pages = atomic_read(&krcp->backoff_page_cache_fill) ?
1 : rcu_min_cached_objs;
- for (i = 0; i < nr_pages; i++) {
+ for (i = READ_ONCE(krcp->nr_bkv_objs); i < nr_pages; i++) {
bnode = (struct kvfree_rcu_bulk_data *)
__get_free_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);