diff options
| author | Omar Sandoval <osandov@fb.com> | 2018-08-21 21:54:55 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-22 10:52:46 -0700 |
| commit | bf53183164dbba00b342df7d2215b33007ed83ed (patch) | |
| tree | 679d8cf52528ddbcffbbf773703fae7fa3225a61 | |
| parent | a8dd9c4df18edc873d244790d163564a5d17626b (diff) | |
| download | linux-bf53183164dbba00b342df7d2215b33007ed83ed.tar.bz2 | |
proc/kcore: don't grab lock for memory hotplug notifier
The memory hotplug notifier kcore_callback() only needs kclist_lock to
prevent races with __kcore_update_ram(), but we can easily eliminate that
race by using an atomic xchg() in __kcore_update_ram(). This is
preparation for converting kclist_lock to an rwsem.
Link: http://lkml.kernel.org/r/0a4bc89f4dbde8b5b2ea309f7b4fb6a85fe29df2.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/proc/kcore.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index b0b9a76f28d6..e83f15a4f66d 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -118,7 +118,7 @@ static void __kcore_update_ram(struct list_head *list) LIST_HEAD(garbage); write_lock(&kclist_lock); - if (kcore_need_update) { + if (xchg(&kcore_need_update, 0)) { list_for_each_entry_safe(pos, tmp, &kclist_head, list) { if (pos->type == KCORE_RAM || pos->type == KCORE_VMEMMAP) @@ -127,7 +127,6 @@ static void __kcore_update_ram(struct list_head *list) list_splice_tail(list, &kclist_head); } else list_splice(list, &garbage); - kcore_need_update = 0; proc_root_kcore->size = get_kcore_size(&nphdr, &size); write_unlock(&kclist_lock); @@ -593,9 +592,8 @@ static int __meminit kcore_callback(struct notifier_block *self, switch (action) { case MEM_ONLINE: case MEM_OFFLINE: - write_lock(&kclist_lock); kcore_need_update = 1; - write_unlock(&kclist_lock); + break; } return NOTIFY_OK; } |