From: Christophe Leroy christophe.leroy@c-s.fr
[ Upstream commit 803d690e68f0c5230183f1a42c7d50a41d16e380 ]
When a process allocates a hugepage, the following leak is reported by kmemleak. This is a false positive which is due to the pointer to the table being stored in the PGD as physical memory address and not virtual memory pointer.
unreferenced object 0xc30f8200 (size 512): comm "mmap", pid 374, jiffies 4872494 (age 627.630s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<e32b68da>] huge_pte_alloc+0xdc/0x1f8 [<9e0df1e1>] hugetlb_fault+0x560/0x8f8 [<7938ec6c>] follow_hugetlb_page+0x14c/0x44c [<afbdb405>] __get_user_pages+0x1c4/0x3dc [<b8fd7cd9>] __mm_populate+0xac/0x140 [<3215421e>] vm_mmap_pgoff+0xb4/0xb8 [<c148db69>] ksys_mmap_pgoff+0xcc/0x1fc [<4fcd760f>] ret_from_syscall+0x0/0x38
See commit a984506c542e2 ("powerpc/mm: Don't report PUDs as memory leaks when using kmemleak") for detailed explanation.
To fix that, this patch tells kmemleak to ignore the allocated hugepage table.
Signed-off-by: Christophe Leroy christophe.leroy@c-s.fr Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/mm/hugetlbpage.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index 4c9e5f9c7a44..e2d929ddad7f 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -19,6 +19,7 @@ #include <linux/moduleparam.h> #include <linux/swap.h> #include <linux/swapops.h> +#include <linux/kmemleak.h> #include <asm/pgtable.h> #include <asm/pgalloc.h> #include <asm/tlb.h> @@ -110,6 +111,8 @@ static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp, for (i = i - 1 ; i >= 0; i--, hpdp--) *hpdp = __hugepd(0); kmem_cache_free(cachep, new); + } else { + kmemleak_ignore(new); } spin_unlock(&mm->page_table_lock); return 0;