The patch titled
Subject: mm/hotplug: treat CMA pages as unmovable
has been added to the -mm tree. Its filename is
mm-hotplug-treat-cma-pages-as-unmovable.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hotplug-treat-cma-pages-as-unmovable.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hotplug-treat-cma-pages-as-unmovable.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Qian Cai <cai@xxxxxx>
Subject: mm/hotplug: treat CMA pages as unmovable
has_unmovable_pages() is used by allocating CMA and gigantic pages as well
as the memory hotplug. The later doesn't know how to offline CMA pool
properly now, but if an unused (free) CMA page is encountered, then
has_unmovable_pages() happily considers it as a free memory and propagates
this up the call chain. Memory offlining code then frees the page without
a proper CMA tear down which leads to an accounting issues. Moreover if
the same memory range is onlined again then the memory never gets back to
the CMA pool.
State after memory offline:
# grep cma /proc/vmstat
nr_free_cma 205824
# cat /sys/kernel/debug/cma/cma-kvm_cma/count
209920
Also, kmemleak still think those memory address are reserved but have
already been used by the buddy allocator after onlining.
Offlined Pages 4096
kmemleak: Cannot insert 0xc000201f7d040008 into the object search tree
(overlaps existing)
Call Trace:
[c00000003dc2faf0] [c000000000884b2c] dump_stack+0xb0/0xf4 (unreliable)
[c00000003dc2fb30] [c000000000424fb4] create_object+0x344/0x380
[c00000003dc2fbf0] [c0000000003d178c] __kmalloc_node+0x3ec/0x860
[c00000003dc2fc90] [c000000000319078] kvmalloc_node+0x58/0x110
[c00000003dc2fcd0] [c000000000484d9c] seq_read+0x41c/0x620
[c00000003dc2fd60] [c0000000004472bc] __vfs_read+0x3c/0x70
[c00000003dc2fd80] [c0000000004473ac] vfs_read+0xbc/0x1a0
[c00000003dc2fdd0] [c00000000044783c] ksys_read+0x7c/0x140
[c00000003dc2fe20] [c00000000000b108] system_call+0x5c/0x70
kmemleak: Kernel memory leak detector disabled
kmemleak: Object 0xc000201cc8000000 (size 13757317120):
kmemleak: comm "swapper/0", pid 0, jiffies 4294937297
kmemleak: min_count = -1
kmemleak: count = 0
kmemleak: flags = 0x5
kmemleak: checksum = 0
kmemleak: backtrace:
cma_declare_contiguous+0x2a4/0x3b0
kvm_cma_reserve+0x11c/0x134
setup_arch+0x300/0x3f8
start_kernel+0x9c/0x6e8
start_here_common+0x1c/0x4b0
kmemleak: Automatic memory scanning thread ended
Link: http://lkml.kernel.org/r/20190413002623.8967-1-cai@xxxxxx
Signed-off-by: Qian Cai <cai@xxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 30 ++++++++++++++++++------------
1 file changed, 18 insertions(+), 12 deletions(-)
--- a/mm/page_alloc.c~mm-hotplug-treat-cma-pages-as-unmovable
+++ a/mm/page_alloc.c
@@ -8005,7 +8005,10 @@ void *__init alloc_large_system_hash(con
bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
int migratetype, int flags)
{
- unsigned long pfn, iter, found;
+ unsigned long found;
+ unsigned long iter = 0;
+ unsigned long pfn = page_to_pfn(page);
+ const char *reason = "unmovable page";
/*
* TODO we could make this much more efficient by not checking every
@@ -8015,17 +8018,20 @@ bool has_unmovable_pages(struct zone *zo
* can still lead to having bootmem allocations in zone_movable.
*/
- /*
- * CMA allocations (alloc_contig_range) really need to mark isolate
- * CMA pageblocks even when they are not movable in fact so consider
- * them movable here.
- */
- if (is_migrate_cma(migratetype) &&
- is_migrate_cma(get_pageblock_migratetype(page)))
- return false;
+ if (is_migrate_cma(get_pageblock_migratetype(page))) {
+ /*
+ * CMA allocations (alloc_contig_range) really need to mark
+ * isolate CMA pageblocks even when they are not movable in fact
+ * so consider them movable here.
+ */
+ if (is_migrate_cma(migratetype))
+ return false;
+
+ reason = "CMA page";
+ goto unmovable;
+ }
- pfn = page_to_pfn(page);
- for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) {
+ for (found = 0; iter < pageblock_nr_pages; iter++) {
unsigned long check = pfn + iter;
if (!pfn_valid_within(check))
@@ -8105,7 +8111,7 @@ bool has_unmovable_pages(struct zone *zo
unmovable:
WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE);
if (flags & REPORT_FAILURE)
- dump_page(pfn_to_page(pfn+iter), "unmovable page");
+ dump_page(pfn_to_page(pfn + iter), reason);
return true;
}
_
Patches currently in -mm which might be from cai@xxxxxx are
slab-store-tagged-freelist-for-off-slab-slabmgmt.patch
mm-hotplug-treat-cma-pages-as-unmovable.patch
mm-compaction-fix-an-undefined-behaviour.patch
initramfs-cleanup-populate_rootfs-fix.patch
