Re: kmemleak for MIPS

From: Maxin John
Date: Tue Mar 29 2011 - 15:36:13 EST


Hi,

I have prepared the combined patch for kmemleak porting to MIPS. After
applying the patch and enabling the kmemleak in Kernel, I can see one
kernel memleak reported during booting itself:
..
..

TCP cubic registered
NET: Registered protocol family 17
NET: Registered protocol family 15
kmemleak: Kernel memory leak detector initialized
rtc_cmos rtc_cmos: setting system clock to 2011-03-29 18:20:41 UTC (1301422841)
kmemleak: Automatic memory scanning thread started
EXT3-fs: barriers not enabled
kjournald starting. Commit interval 5 seconds
EXT3-fs (hda1): mounted filesystem with ordered data mode
VFS: Mounted root (ext3 filesystem) readonly on device 3:1.
Freeing prom memory: 956k freed
Freeing unused kernel memory: 244k freed
modprobe: FATAL: Could not load
/lib/modules/2.6.38-08826-g1788c20-dirty/modules.dep: No such file or
directory

INIT: version 2.86 booting
Starting the hotplug events dispatcher: udevdudevd (863):
/proc/863/oom_adj is deprecated, please use /proc/863/oom_score_adj
instead.
.
Synthesizing the initial hotplug events...done.
Waiting for /dev to be fully populated...kmemleak: 1 new suspected
memory leaks (see /sys/kernel/debug/kmemleak)
....
....

debian-mips:~#
debian-mips:~# mount -t debugfs nodev /sys/kernel/debug/
debian-mips:~# cat /sys/kernel/debug/kmemleak
unreferenced object 0x8f90d000 (size 4096):
comm "swapper", pid 1, jiffies 4294937330 (age 815.000s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<80529644>] alloc_large_system_hash+0x2f8/0x410
[<805383b4>] udp_table_init+0x4c/0x158
[<805384dc>] udp_init+0x1c/0x94
[<8053889c>] inet_init+0x184/0x2a0
[<80100584>] do_one_initcall+0x174/0x1e0
[<8051f348>] kernel_init+0xe4/0x174
[<80103d4c>] kernel_thread_helper+0x10/0x18


The standard kmemleak test case is behaving as expected. Based on
this, I think, we can say that the kmemleak support for MIPS is
working.

Please let me know your comments.

Signed-off-by: Maxin B. John <maxin.john@xxxxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
---
diff --git a/arch/mips/include/asm/cache.h b/arch/mips/include/asm/cache.h
index 650ac9b..b4db69f 100644
--- a/arch/mips/include/asm/cache.h
+++ b/arch/mips/include/asm/cache.h
@@ -17,6 +17,6 @@
#define SMP_CACHE_SHIFT L1_CACHE_SHIFT
#define SMP_CACHE_BYTES L1_CACHE_BYTES

-#define __read_mostly __attribute__((__section__(".data.read_mostly")))
+#define __read_mostly __attribute__((__section__(".data..read_mostly")))

#endif /* _ASM_CACHE_H */
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 832afbb..501204d 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -68,12 +68,14 @@ SECTIONS
RODATA

/* writeable */
+ _sdata = .; /* Start of data section */
.data : { /* Data */
. = . + DATAOFFSET; /* for CONFIG_MAPPED_KERNEL */

INIT_TASK_DATA(PAGE_SIZE)
NOSAVE_DATA
CACHELINE_ALIGNED_DATA(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
+ READ_MOSTLY_DATA(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
DATA_DATA
CONSTRUCTORS
}
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index df9234c..5042421 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -398,7 +398,7 @@ config SLUB_STATS
config DEBUG_KMEMLEAK
bool "Kernel memory leak detector"
depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
- (X86 || ARM || PPC || S390 || SPARC64 || SUPERH ||
MICROBLAZE || TILE)
+ (X86 || ARM || PPC || MIPS || S390 || SPARC64 ||
SUPERH || MICROBLAZE || TILE)

select DEBUG_FS if SYSFS
select STACKTRACE if STACKTRACE_SUPPORT
--
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