From 21e516b913c137cf955e50359e499c0994d4b9a9 Mon Sep 17 00:00:00 2001 From: Hariom Panthi Date: Wed, 24 Apr 2024 16:48:38 +0530 Subject: [PATCH] mm: vmalloc: dump page owner info if page is already mapped 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! Link: https://lkml.kernel.org/r/20240424111838.3782931-2-hariom1.p@samsung.com Signed-off-by: Hariom Panthi Cc: Christoph Hellwig Cc: Lorenzo Stoakes Cc: Maninder Singh Cc: Oscar Salvador Cc: Rohit Thapliyal Cc: Uladzislau Rezki (Sony) Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/vmalloc.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 6856fad1a8f8..b00c2f5f70ea 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -42,6 +42,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -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);