[PATCH 5.15.y] Revert "mm: kmemleak: take a full lowmem check in kmemleak_*_phys()"

[yee.lee]

From: Yee Lee <yee.lee@xxxxxxxxxxxx>

This reverts commit 23c2d497de21f25898fbea70aeb292ab8acc8c94.

Commit 23c2d497de21 ("mm: kmemleak: take a full lowmem check in
kmemleak_*_phys()") brought false leak alarms on some archs like arm64
that does not init pfn boundary in early booting. The final solution
lands on linux-6.0: commit 0c24e061196c ("mm: kmemleak: add rbtree and
store physical address for objects allocated with PA").

Revert this commit before linux-6.0. The original issue of invalid PA
can be mitigated by additional check in devicetree.

The false alarm report is as following: 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 pacth is also applicable to linux-5.17.y/linux-5.18.y/linux-5.19.y

Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Yee Lee <yee.lee@xxxxxxxxxxxx>
---
 mm/kmemleak.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 859303aae180..b78861b8e013 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1125,7 +1125,7 @@ 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 (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
 		kmemleak_alloc(__va(phys), size, min_count, gfp);
 }
 EXPORT_SYMBOL(kmemleak_alloc_phys);
@@ -1139,7 +1139,7 @@ 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 (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
 		kmemleak_free_part(__va(phys), size);
 }
 EXPORT_SYMBOL(kmemleak_free_part_phys);
@@ -1151,7 +1151,7 @@ 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 (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
 		kmemleak_not_leak(__va(phys));
 }
 EXPORT_SYMBOL(kmemleak_not_leak_phys);
@@ -1163,7 +1163,7 @@ 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 (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
 		kmemleak_ignore(__va(phys));
 }
 EXPORT_SYMBOL(kmemleak_ignore_phys);
-- 
2.18.0