Re: [PATCH] mm: kmemleak: Skip check in kmemleak_*_phys when pfn bound is not ready
From: patrick wang <hidden>
Date: 2022-05-27 10:20:30
Also in:
linux-mediatek, linux-mm, lkml
On Fri, May 27, 2022 at 11:25 AM [off-list ref] wrote:
From: Yee Lee <redacted> In some archs (arm64), memblock allocates memory in boot time when the pfn boundary (max_pfn/min_pfn) is not ready. The lowmen checks in kmemleak_*_phys() drop those blocks and cause some false leak alarms on common kernel objects.
If I understand correctly, if those blocks are dropped, they will not be added as kmemleak objects. So how could this affect other objects? Thanks, Patrick
quoted hunk ↗ jump to hunk
Kmemleak output: (Qemu/arm64) unreferenced object 0xffff0000c0170a00 (size 128): comm "swapper/0", pid 1, jiffies 4294892404 (age 126.208s) hex dump (first 32 bytes): 62 61 73 65 00 00 00 00 00 00 00 00 00 00 00 00 base............ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<(____ptrval____)>] __kmalloc_track_caller+0x1b0/0x2e4 [<(____ptrval____)>] kstrdup_const+0x8c/0xc4 [<(____ptrval____)>] kvasprintf_const+0xbc/0xec [<(____ptrval____)>] kobject_set_name_vargs+0x58/0xe4 [<(____ptrval____)>] kobject_add+0x84/0x100 [<(____ptrval____)>] __of_attach_node_sysfs+0x78/0xec [<(____ptrval____)>] of_core_init+0x68/0x104 [<(____ptrval____)>] driver_init+0x28/0x48 [<(____ptrval____)>] do_basic_setup+0x14/0x28 [<(____ptrval____)>] kernel_init_freeable+0x110/0x178 [<(____ptrval____)>] kernel_init+0x20/0x1a0 [<(____ptrval____)>] ret_from_fork+0x10/0x20 This patch relaxs the boundary checking in kmemleak_*_phys api if max_low_pfn is uninitialzed. Fixes: 23c2d4 (mm: kmemleak: take a full lowmem check in kmemleak_*_phy) Signed-off-by: Yee Lee <redacted> --- mm/kmemleak.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)diff --git a/mm/kmemleak.c b/mm/kmemleak.c index a182f5ddaf68..6b2af544aa0f 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c@@ -1132,7 +1132,7 @@ EXPORT_SYMBOL(kmemleak_no_scan); void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, int min_count, gfp_t gfp) { - if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn) + if (!max_low_pfn || (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)) kmemleak_alloc(__va(phys), size, min_count, gfp); } EXPORT_SYMBOL(kmemleak_alloc_phys);@@ -1146,7 +1146,7 @@ EXPORT_SYMBOL(kmemleak_alloc_phys); */ void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size) { - if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn) + if (!max_low_pfn || (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)) kmemleak_free_part(__va(phys), size); } EXPORT_SYMBOL(kmemleak_free_part_phys);@@ -1158,7 +1158,7 @@ EXPORT_SYMBOL(kmemleak_free_part_phys); */ void __ref kmemleak_not_leak_phys(phys_addr_t phys) { - if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn) + if (!max_low_pfn || (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)) kmemleak_not_leak(__va(phys)); } EXPORT_SYMBOL(kmemleak_not_leak_phys);@@ -1170,7 +1170,7 @@ EXPORT_SYMBOL(kmemleak_not_leak_phys); */ void __ref kmemleak_ignore_phys(phys_addr_t phys) { - if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn) + if (!max_low_pfn || (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)) kmemleak_ignore(__va(phys)); } EXPORT_SYMBOL(kmemleak_ignore_phys); --2.18.0
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