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authorLang Yu <lang.yu@amd.com>2022-02-04 07:49:37 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-02-04 20:25:05 +0300
commitc10a0f877fe007021d70f9cada240f42adc2b5db (patch)
tree8bf9f7e41f568a786715a365cb6c30c98af0687d
parent520ba724061cef59763e2b6f5b26e8387c2e5822 (diff)
downloadlinux-c10a0f877fe007021d70f9cada240f42adc2b5db.tar.xz
mm/kmemleak: avoid scanning potential huge holes
When using devm_request_free_mem_region() and devm_memremap_pages() to add ZONE_DEVICE memory, if requested free mem region's end pfn were huge(e.g., 0x400000000), the node_end_pfn() will be also huge (see move_pfn_range_to_zone()). Thus it creates a huge hole between node_start_pfn() and node_end_pfn(). We found on some AMD APUs, amdkfd requested such a free mem region and created a huge hole. In such a case, following code snippet was just doing busy test_bit() looping on the huge hole. for (pfn = start_pfn; pfn < end_pfn; pfn++) { struct page *page = pfn_to_online_page(pfn); if (!page) continue; ... } So we got a soft lockup: watchdog: BUG: soft lockup - CPU#6 stuck for 26s! [bash:1221] CPU: 6 PID: 1221 Comm: bash Not tainted 5.15.0-custom #1 RIP: 0010:pfn_to_online_page+0x5/0xd0 Call Trace: ? kmemleak_scan+0x16a/0x440 kmemleak_write+0x306/0x3a0 ? common_file_perm+0x72/0x170 full_proxy_write+0x5c/0x90 vfs_write+0xb9/0x260 ksys_write+0x67/0xe0 __x64_sys_write+0x1a/0x20 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae I did some tests with the patch. (1) amdgpu module unloaded before the patch: real 0m0.976s user 0m0.000s sys 0m0.968s after the patch: real 0m0.981s user 0m0.000s sys 0m0.973s (2) amdgpu module loaded before the patch: real 0m35.365s user 0m0.000s sys 0m35.354s after the patch: real 0m1.049s user 0m0.000s sys 0m1.042s Link: https://lkml.kernel.org/r/20211108140029.721144-1-lang.yu@amd.com Signed-off-by: Lang Yu <lang.yu@amd.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/kmemleak.c13
1 files changed, 7 insertions, 6 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index dc3758fdba68..7580baa76af1 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1410,7 +1410,8 @@ static void kmemleak_scan(void)
{
unsigned long flags;
struct kmemleak_object *object;
- int i;
+ struct zone *zone;
+ int __maybe_unused i;
int new_leaks = 0;
jiffies_last_scan = jiffies;
@@ -1450,9 +1451,9 @@ static void kmemleak_scan(void)
* Struct page scanning for each node.
*/
get_online_mems();
- for_each_online_node(i) {
- unsigned long start_pfn = node_start_pfn(i);
- unsigned long end_pfn = node_end_pfn(i);
+ for_each_populated_zone(zone) {
+ unsigned long start_pfn = zone->zone_start_pfn;
+ unsigned long end_pfn = zone_end_pfn(zone);
unsigned long pfn;
for (pfn = start_pfn; pfn < end_pfn; pfn++) {
@@ -1461,8 +1462,8 @@ static void kmemleak_scan(void)
if (!page)
continue;
- /* only scan pages belonging to this node */
- if (page_to_nid(page) != i)
+ /* only scan pages belonging to this zone */
+ if (page_zone(page) != zone)
continue;
/* only scan if page is in use */
if (page_count(page) == 0)