mm: kmemleak: fix upper boundary check for physical address objects

Memblock allocations are registered by kmemleak separately, based on their
physical address.  During the scanning stage, it checks whether an object
is within the min_low_pfn and max_low_pfn boundaries and ignores it
otherwise.

With the recent addition of __percpu pointer leak detection (commit
6c99d4eb7c5e ("kmemleak: enable tracking for percpu pointers")), kmemleak
started reporting leaks in setup_zone_pageset() and
setup_per_cpu_pageset().  These were caused by the node_data[0] object
(initialised in alloc_node_data()) ending on the PFN_PHYS(max_low_pfn)
boundary.  The non-strict upper boundary check introduced by commit
84c326299191 ("mm: kmemleak: check physical address when scan") causes the
pg_data_t object to be ignored (not scanned) and the __percpu pointers it
contains to be reported as leaks.

Make the max_low_pfn upper boundary check strict when deciding whether to
ignore a physical address object and not scan it.

Link: https://lkml.kernel.org/r/20250127184233.2974311-1-catalin.marinas@arm.com
Fixes: 84c326299191 ("mm: kmemleak: check physical address when scan")
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Jakub Kicinski <kuba@kernel.org>
Tested-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Cc: Patrick Wang <patrick.wang.shcn@gmail.com>
Cc: <stable@vger.kernel.org>	[6.0.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 982bb5ef323310dae6947f51f495f94ea022a8dc..c6ed68604136a3108fa161b036a651effff4f6b9 100644 (file)
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1689,7 +1689,7 @@ static void kmemleak_scan(void)
                        unsigned long phys = object->pointer;
 
                        if (PHYS_PFN(phys) < min_low_pfn ||
-                           PHYS_PFN(phys + object->size) >= max_low_pfn)
+                           PHYS_PFN(phys + object->size) > max_low_pfn)
                                __paint_it(object, KMEMLEAK_BLACK);
                }