mm: kmemleak: scan .data.ro_after_init

Limit the number of kmemleak false positives by including
.data.ro_after_init in memory scanning.  To achieve this we need to add
symbols for start and end of the section to the linker scripts.

The problem was been uncovered by commit 56989f6d8568 ("genetlink: mark
families as __ro_after_init").

Link: http://lkml.kernel.org/r/1478274173-15218-1-git-send-email-jakub.kicinski@netronome.com
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 000e6e91f6a0630c53f35519d450fccf02479e55..3667d20e997f3ccac943438ad2e03588795afb33 100644 (file)
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -62,9 +62,11 @@ SECTIONS
 
        . = ALIGN(PAGE_SIZE);
        __start_ro_after_init = .;
+       __start_data_ro_after_init = .;
        .data..ro_after_init : {
                 *(.data..ro_after_init)
        }
+       __end_data_ro_after_init = .;
        EXCEPTION_TABLE(16)
        . = ALIGN(PAGE_SIZE);
        __end_ro_after_init = .;

diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index af0254c0942476f67e92c08f8e75918e529b4994..4df64a1fc09e7aab7f88cd4afe73928228930147 100644 (file)
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -14,6 +14,8 @@
  * [_sdata, _edata]: contains .data.* sections, may also contain .rodata.*
  *                   and/or .init.* sections.
  * [__start_rodata, __end_rodata]: contains .rodata.* sections
+ * [__start_data_ro_after_init, __end_data_ro_after_init]:
+ *                  contains data.ro_after_init section
  * [__init_begin, __init_end]: contains .init.* sections, but .init.text.*
  *                   may be out of this range on some architectures.
  * [_sinittext, _einittext]: contains .init.text.* sections
@@ -31,6 +33,7 @@ extern char _data[], _sdata[], _edata[];
 extern char __bss_start[], __bss_stop[];
 extern char __init_begin[], __init_end[];
 extern char _sinittext[], _einittext[];
+extern char __start_data_ro_after_init[], __end_data_ro_after_init[];
 extern char _end[];
 extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[];
 extern char __kprobes_text_start[], __kprobes_text_end[];

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 30747960bc54a29496eb134ebff26bfcb67e2fd7..31e1d639abedacd87828613416bce5c459694fc8 100644 (file)
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -259,7 +259,10 @@
  * own by defining an empty RO_AFTER_INIT_DATA.
  */
 #ifndef RO_AFTER_INIT_DATA
-#define RO_AFTER_INIT_DATA *(.data..ro_after_init)
+#define RO_AFTER_INIT_DATA                                             \
+       __start_data_ro_after_init = .;                                 \
+       *(.data..ro_after_init)                                         \
+       __end_data_ro_after_init = .;
 #endif
 
 /*

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index e5355a5b423fa9fd61a77ebf7b94819ec2e199df..d1380ed93fdf084d5043a2fb1f8bb3e476cb7bf9 100644 (file)
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1414,6 +1414,7 @@ static void kmemleak_scan(void)
        /* data/bss scanning */
        scan_large_block(_sdata, _edata);
        scan_large_block(__bss_start, __bss_stop);
+       scan_large_block(__start_data_ro_after_init, __end_data_ro_after_init);
 
 #ifdef CONFIG_SMP
        /* per-cpu sections scanning */