[PATCH 2/2] mm: vmalloc: dump page owner info if page is already mapped
From: Hariom Panthi
Date: Wed Apr 24 2024 - 07:22:34 EST
In vmap_pte_range, BUG_ON is called when page is already mapped,
It doesn't give enough information to debug further.
Dumping page owner information alongwith BUG_ON will be more useful
in case of multiple page mapping.
Example:
[ 14.552875] page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10b923
[ 14.553440] flags: 0xbffff0000000000(node=0|zone=2|lastcpupid=0x3ffff)
[ 14.554001] page_type: 0xffffffff()
[ 14.554783] raw: 0bffff0000000000 0000000000000000 dead000000000122 0000000000000000
[ 14.555230] raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
[ 14.555768] page dumped because: remapping already mapped page
[ 14.556172] page_owner tracks the page as allocated
[ 14.556482] page last allocated via order 0, migratetype Unmovable, gfp_mask 0xcc0(GFP_KERNEL), pid 80, tgid 80 (insmod), ts 14552004992, free_ts 0
[ 14.557286] prep_new_page+0xa8/0x10c
[ 14.558052] get_page_from_freelist+0x7f8/0x1248
[ 14.558298] __alloc_pages+0x164/0x2b4
[ 14.558514] alloc_pages_mpol+0x88/0x230
[ 14.558904] alloc_pages+0x4c/0x7c
[ 14.559157] load_module+0x74/0x1af4
[ 14.559361] __do_sys_init_module+0x190/0x1fc
[ 14.559615] __arm64_sys_init_module+0x1c/0x28
[ 14.559883] invoke_syscall+0x44/0x108
[ 14.560109] el0_svc_common.constprop.0+0x40/0xe0
[ 14.560371] do_el0_svc_compat+0x1c/0x34
[ 14.560600] el0_svc_compat+0x2c/0x80
[ 14.560820] el0t_32_sync_handler+0x90/0x140
[ 14.561040] el0t_32_sync+0x194/0x198
[ 14.561329] page_owner free stack trace missing
[ 14.562049] ------------[ cut here ]------------
[ 14.562314] kernel BUG at mm/vmalloc.c:113!
Signed-off-by: Hariom Panthi <hariom1.p@xxxxxxxxxxx>
---
replaced dump_page_owner() with dump_page() as per Andrew's suggestion
mm/vmalloc.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 68fa001648cc..bc74eb406c0a 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -42,6 +42,7 @@
#include <linux/sched/mm.h>
#include <asm/tlbflush.h>
#include <asm/shmparam.h>
+#include <linux/page_owner.h>
#define CREATE_TRACE_POINTS
#include <trace/events/vmalloc.h>
@@ -96,6 +97,7 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
{
pte_t *pte;
u64 pfn;
+ struct page *page;
unsigned long size = PAGE_SIZE;
pfn = phys_addr >> PAGE_SHIFT;
@@ -103,7 +105,13 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
if (!pte)
return -ENOMEM;
do {
- BUG_ON(!pte_none(ptep_get(pte)));
+ if (!pte_none(ptep_get(pte))) {
+ if (pfn_valid(pfn)) {
+ page = pfn_to_page(pfn);
+ dump_page(page, "remapping already mapped page");
+ }
+ BUG();
+ }
#ifdef CONFIG_HUGETLB_PAGE
size = arch_vmap_pte_range_map_size(addr, end, pfn, max_page_shift);
--
2.25.1