kmemleak: powerpc: skip scanning holes in the .bss section (298a32b1) · Commits · 戴 / test

Commit ("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 when it scans the .bss section with unmapped pages. This patch creates dedicated kmemleak objects for the .data, .bss and potentially .data..ro_after_init sections to allow partial freeing via the kmemleak_free_part() in the powerpc kvm_free_tmp() function. Link: http://lkml.kernel.org/r/20190321171917.62049-1-catalin.marinas@arm.com Signed-off-by:

Catalin Marinas <catalin.marinas@arm.com> Reported-by:

Qian Cai <cai@lca.pw> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Tested-by:

Qian Cai <cai@lca.pw> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Avi Kivity <avi@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

arch/powerpc/kernel/kvm.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -22,6 +22,7 @@
		#include <linux/kvm_host.h>
		#include <linux/init.h>
		#include <linux/export.h>
		#include <linux/kmemleak.h>
		#include <linux/kvm_para.h>
		#include <linux/slab.h>
		#include <linux/of.h>
		@@ -712,6 +713,12 @@ static void kvm_use_magic_page(void)

		static __init void kvm_free_tmp(void)
		{
		/*
		* Inform kmemleak about the hole in the .bss section since the
		* corresponding pages will be unmapped with DEBUG_PAGEALLOC=y.
		*/
		kmemleak_free_part(&kvm_tmp[kvm_tmp_index],
		ARRAY_SIZE(kvm_tmp) - kvm_tmp_index);
		free_reserved_area(&kvm_tmp[kvm_tmp_index],
		&kvm_tmp[ARRAY_SIZE(kvm_tmp)], -1, NULL);
		}

mm/kmemleak.c

+11 −5

Original line number	Diff line number	Diff line
		@@ -1529,11 +1529,6 @@ static void kmemleak_scan(void)
		}
		rcu_read_unlock();

		/* data/bss scanning */
		scan_large_block(_sdata, _edata);
		scan_large_block(__bss_start, __bss_stop);
		scan_large_block(__start_ro_after_init, __end_ro_after_init);

		#ifdef CONFIG_SMP
		/* per-cpu sections scanning */
		for_each_possible_cpu(i)
		@@ -2071,6 +2066,17 @@ void __init kmemleak_init(void)
		}
		local_irq_restore(flags);

		/* register the data/bss sections */
		create_object((unsigned long)_sdata, _edata - _sdata,
		KMEMLEAK_GREY, GFP_ATOMIC);
		create_object((unsigned long)__bss_start, __bss_stop - __bss_start,
		KMEMLEAK_GREY, GFP_ATOMIC);
		/* only register .data..ro_after_init if not within .data */
		if (__start_ro_after_init < _sdata \|\| __end_ro_after_init > _edata)
		create_object((unsigned long)__start_ro_after_init,
		__end_ro_after_init - __start_ro_after_init,
		KMEMLEAK_GREY, GFP_ATOMIC);

		/*
		* This is the point where tracking allocations is safe. Automatic
		* scanning is started during the late initcall. Add the early logged

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