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

BugLink: https://bugs.launchpad.net/bugs/2114239

commit 488b5b9eca68497b533ced059be5eff19578bbca upstream.

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
84c3262991 ("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: 84c3262991 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Noah Wager <noah.wager@canonical.com>
Signed-off-by: Mehmet Basaran <mehmet.basaran@canonical.com>

mm/kmemleak.c

@@ -1619,7 +1619,7 @@ 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);
 		}