Patch "Revert "mm: kmemleak: take a full lowmem check in kmemleak_*_phys()"" has been added to the 5.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    Revert "mm: kmemleak: take a full lowmem check in kmemleak_*_phys()"

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     revert-mm-kmemleak-take-a-full-lowmem-check-in-kmemleak_-_phys.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From yee.lee@mediatek.com  Thu Sep  8 19:05:17 2022
From: <yee.lee@mediatek.com>
Date: Tue, 6 Sep 2022 15:03:06 +0800
Subject: Revert "mm: kmemleak: take a full lowmem check in kmemleak_*_phys()"
To: <linux-kernel@vger.kernel.org>
Cc: <patrick.wang.shcn@gmail.com>, Yee Lee <yee.lee@mediatek.com>, <stable@vger.kernel.org>, Catalin Marinas <catalin.marinas@arm.com>, "Andrew Morton" <akpm@linux-foundation.org>, Matthias Brugger <matthias.bgg@gmail.com>, "open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>, "moderated list:ARM/Mediatek SoC support"  <linux-arm-kernel@lists.infradead.org>, "moderated list:ARM/Mediatek SoC support"  <linux-mediatek@lists.infradead.org>
Message-ID: <20220906070309.18809-1-yee.lee@mediatek.com>

From: Yee Lee <yee.lee@mediatek.com>

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@vger.kernel.org>
Signed-off-by: Yee Lee <yee.lee@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/kmemleak.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1123,7 +1123,7 @@ 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);
@@ -1137,7 +1137,7 @@ 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);
@@ -1149,7 +1149,7 @@ 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);
@@ -1161,7 +1161,7 @@ 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);


Patches currently in stable-queue which might be from yee.lee@mediatek.com are

queue-5.4/revert-mm-kmemleak-take-a-full-lowmem-check-in-kmemleak_-_phys.patch