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percpu: make allocation failures more verbose

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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>
This commit is contained in:
Tejun Heo 2009-09-29 09:17:58 +09:00
parent 635b75fc18
commit f2badb0c95
1 changed files with 18 additions and 2 deletions
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20
mm/percpu.c
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@ -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;
}