The patch titled
Subject: kmemleak: skip scanning holes in the .bss section
has been removed from the -mm tree. Its filename was
kmemleak-skip-scanning-holes-in-the-bss-section.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Qian Cai <cai@xxxxxx>
Subject: kmemleak: skip scanning holes in the .bss section
2d4f567103ff ("KVM: PPC: Introduce kvm_tmp framework") adds kvm_tmp[] into
the .bss section and then free the rest of unused spaces back to the page
allocator.
kernel_init
kvm_guest_init
kvm_free_tmp
free_reserved_area
free_unref_page
free_unref_page_prepare
With DEBUG_PAGEALLOC=y, it will unmap those pages from kernel. As the
result, kmemleak scan will trigger a panic below when it scans the .bss
section with unmapped pages.
Since this is done way before the first kmemleak_scan(), just go lockless
to make the implementation simple and skip those pages when scanning the
.bss section. Later, those pages could be tracked by kmemleak again once
allocated by the page allocator. Overall, this is such a special case, so
no need to make it a generic to let kmemleak gain an ability to skip
blocks in scan_large_block().
BUG: Unable to handle kernel data access at 0xc000000001610000
Faulting instruction address: 0xc0000000003cc178
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA pSeries
CPU: 3 PID: 130 Comm: kmemleak Kdump: loaded Not tainted 5.0.0+ #9
REGS: c0000004b05bf940 TRAP: 0300 Not tainted (5.0.0+)
NIP [c0000000003cc178] scan_block+0xa8/0x190
LR [c0000000003cc170] scan_block+0xa0/0x190
Call Trace:
[c0000004b05bfbd0] [c0000000003cc170] scan_block+0xa0/0x190 (unreliable)
[c0000004b05bfc30] [c0000000003cc2c0] scan_large_block+0x60/0xa0
[c0000004b05bfc70] [c0000000003ccc64] kmemleak_scan+0x254/0x960
[c0000004b05bfd40] [c0000000003cdd50] kmemleak_scan_thread+0xec/0x12c
[c0000004b05bfdb0] [c000000000104388] kthread+0x1b8/0x1c0
[c0000004b05bfe20] [c00000000000b364] ret_from_kernel_thread+0x5c/0x78
Instruction dump:
7fa3eb78 4844667d 60000000 60000000 60000000 60000000 3bff0008 7fbcf840
409d00b8 4bfffeed 2fa30000 409e00ac <e87f0000> e93e0128 7fa91840
419dffdc
akpm: this is very crude. It can be made into something more
sophisticated if and when another caller is identified.
[akpm@xxxxxxxxxxxxxxxxxxxx: make kmemleak_bss_hole __init]
[cai@xxxxxx: mark kmemleak_bss_hole() declaration __init]
Link: http://lkml.kernel.org/r/20190313145717.46369-1-cai@xxxxxx
Link: http://lkml.kernel.org/r/20190312191412.28656-1-cai@xxxxxx
Signed-off-by: Qian Cai <cai@xxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/kvm.c | 3 +++
include/linux/kmemleak.h | 4 ++++
mm/kmemleak.c | 25 ++++++++++++++++++++++++-
3 files changed, 31 insertions(+), 1 deletion(-)
--- a/arch/powerpc/kernel/kvm.c~kmemleak-skip-scanning-holes-in-the-bss-section
+++ a/arch/powerpc/kernel/kvm.c
@@ -26,6 +26,7 @@
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/pagemap.h>
+#include <linux/kmemleak.h>
#include <asm/reg.h>
#include <asm/sections.h>
@@ -712,6 +713,8 @@ static void kvm_use_magic_page(void)
static __init void kvm_free_tmp(void)
{
+ kmemleak_bss_hole(&kvm_tmp[kvm_tmp_index],
+ &kvm_tmp[ARRAY_SIZE(kvm_tmp)]);
free_reserved_area(&kvm_tmp[kvm_tmp_index],
&kvm_tmp[ARRAY_SIZE(kvm_tmp)], -1, NULL);
}
--- a/include/linux/kmemleak.h~kmemleak-skip-scanning-holes-in-the-bss-section
+++ a/include/linux/kmemleak.h
@@ -46,6 +46,7 @@ extern void kmemleak_alloc_phys(phys_add
extern void kmemleak_free_part_phys(phys_addr_t phys, size_t size) __ref;
extern void kmemleak_not_leak_phys(phys_addr_t phys) __ref;
extern void kmemleak_ignore_phys(phys_addr_t phys) __ref;
+extern void kmemleak_bss_hole(void *start, void *stop) __init;
static inline void kmemleak_alloc_recursive(const void *ptr, size_t size,
int min_count, slab_flags_t flags,
@@ -131,6 +132,9 @@ static inline void kmemleak_not_leak_phy
static inline void kmemleak_ignore_phys(phys_addr_t phys)
{
}
+static inline void kmemleak_bss_hole(void *start, void *stop)
+{
+}
#endif /* CONFIG_DEBUG_KMEMLEAK */
--- a/mm/kmemleak.c~kmemleak-skip-scanning-holes-in-the-bss-section
+++ a/mm/kmemleak.c
@@ -237,6 +237,10 @@ static int kmemleak_skip_disable;
/* If there are leaks that can be reported */
static bool kmemleak_found_leaks;
+/* Skip scanning of a range in the .bss section. */
+static void *bss_hole_start;
+static void *bss_hole_stop;
+
static bool kmemleak_verbose;
module_param_named(verbose, kmemleak_verbose, bool, 0600);
@@ -1265,6 +1269,18 @@ void __ref kmemleak_ignore_phys(phys_add
}
EXPORT_SYMBOL(kmemleak_ignore_phys);
+/**
+ * kmemleak_bss_hole - skip scanning a range in the .bss section
+ *
+ * @start: start of the range
+ * @stop: end of the range
+ */
+void __init kmemleak_bss_hole(void *start, void *stop)
+{
+ bss_hole_start = start;
+ bss_hole_stop = stop;
+}
+
/*
* Update an object's checksum and return true if it was modified.
*/
@@ -1531,7 +1547,14 @@ static void kmemleak_scan(void)
/* data/bss scanning */
scan_large_block(_sdata, _edata);
- scan_large_block(__bss_start, __bss_stop);
+
+ if (bss_hole_start) {
+ scan_large_block(__bss_start, bss_hole_start);
+ scan_large_block(bss_hole_stop, __bss_stop);
+ } else {
+ scan_large_block(__bss_start, __bss_stop);
+ }
+
scan_large_block(__start_ro_after_init, __end_ro_after_init);
#ifdef CONFIG_SMP
_
Patches currently in -mm which might be from cai@xxxxxx are
kasan-fix-variable-tag-set-but-not-used-warning.patch
mm-debug-add-a-cast-to-u64-for-atomic64_read.patch
mm-hotplug-fix-offline-undo_isolate_page_range.patch
mm-hotplug-fix-offline-undo_isolate_page_range-v4.patch
mm-compaction-abort-search-if-isolation-fails-v2.patch
mm-hotplug-fix-notification-in-offline-error-path.patch
mm-fix-a-wrong-flag-in-set_migratetype_isolate.patch
mm-compaction-fix-an-undefined-behaviour.patch
