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authorTejun Heo <tj@kernel.org>2009-09-29 09:17:58 +0900
committerTejun Heo <tj@kernel.org>2009-09-29 09:17:58 +0900
commitf2badb0c950ed308be9b321203b9c8d341690cd4 (patch)
tree5da0e7493192f97be604e257fd10847ae3a27504 /mm/percpu.c
parent635b75fc18858d3522e481c043de764766db923c (diff)
downloadvexpress-lsk-f2badb0c950ed308be9b321203b9c8d341690cd4.tar.gz
percpu: make allocation failures more verbose
Warn and dump stack when percpu allocation fails. percpu allocator is still young and unchecked NULL percpu pointer usage can result in random memory corruption when combined with the pointer shifting in access macros. Allocation failures should be rare and the warning message will be disabled after certain times. Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'mm/percpu.c')
-rw-r--r--mm/percpu.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/mm/percpu.c b/mm/percpu.c
index 83617ca3ba5..4a048abad04 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1043,7 +1043,9 @@ static struct pcpu_chunk *alloc_pcpu_chunk(void)
*/
static void *pcpu_alloc(size_t size, size_t align, bool reserved)
{
+ static int warn_limit = 10;
struct pcpu_chunk *chunk;
+ const char *err;
int slot, off;
if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
@@ -1059,11 +1061,14 @@ static void *pcpu_alloc(size_t size, size_t align, bool reserved)
if (reserved && pcpu_reserved_chunk) {
chunk = pcpu_reserved_chunk;
if (size > chunk->contig_hint ||
- pcpu_extend_area_map(chunk) < 0)
+ pcpu_extend_area_map(chunk) < 0) {
+ err = "failed to extend area map of reserved chunk";
goto fail_unlock;
+ }
off = pcpu_alloc_area(chunk, size, align);
if (off >= 0)
goto area_found;
+ err = "alloc from reserved chunk failed";
goto fail_unlock;
}
@@ -1080,6 +1085,7 @@ restart:
case 1:
goto restart; /* pcpu_lock dropped, restart */
default:
+ err = "failed to extend area map";
goto fail_unlock;
}
@@ -1093,8 +1099,10 @@ restart:
spin_unlock_irq(&pcpu_lock);
chunk = alloc_pcpu_chunk();
- if (!chunk)
+ if (!chunk) {
+ err = "failed to allocate new chunk";
goto fail_unlock_mutex;
+ }
spin_lock_irq(&pcpu_lock);
pcpu_chunk_relocate(chunk, -1);
@@ -1107,6 +1115,7 @@ area_found:
if (pcpu_populate_chunk(chunk, off, size)) {
spin_lock_irq(&pcpu_lock);
pcpu_free_area(chunk, off);
+ err = "failed to populate";
goto fail_unlock;
}
@@ -1119,6 +1128,13 @@ fail_unlock:
spin_unlock_irq(&pcpu_lock);
fail_unlock_mutex:
mutex_unlock(&pcpu_alloc_mutex);
+ if (warn_limit) {
+ pr_warning("PERCPU: allocation failed, size=%zu align=%zu, "
+ "%s\n", size, align, err);
+ dump_stack();
+ if (!--warn_limit)
+ pr_info("PERCPU: limit reached, disable warning\n");
+ }
return NULL;
}