* [PATCH 0/4] debug-pagealloc improvements
@ 2011-08-22 16:29 ` Akinobu Mita
0 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-22 16:29 UTC (permalink / raw)
To: linux-kernel, linux-mm, akpm; +Cc: Akinobu Mita
This patch series includes three improvements for the debug-pagealloc
feature for no-architecture support (!ARCH_SUPPORTS_DEBUG_PAGEALLOC) and
one introduction of the new string library function (memchr_inv).
Akinobu Mita (4):
debug-pagealloc: use plain __ratelimit() instead of
printk_ratelimit()
debug-pagealloc: add support for highmem pages
string: introduce memchr_inv
debug-pagealloc: use memchr_inv
fs/logfs/logfs.h | 1 -
fs/logfs/super.c | 22 --------------
include/linux/string.h | 1 +
lib/string.c | 54 +++++++++++++++++++++++++++++++++++
mm/debug-pagealloc.c | 73 +++++++++++++++++++++++------------------------
mm/slub.c | 47 +-----------------------------
6 files changed, 93 insertions(+), 105 deletions(-)
--
1.7.4.4
^ permalink raw reply [flat|nested] 30+ messages in thread
* [PATCH 0/4] debug-pagealloc improvements
@ 2011-08-22 16:29 ` Akinobu Mita
0 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-22 16:29 UTC (permalink / raw)
To: linux-kernel, linux-mm, akpm; +Cc: Akinobu Mita
This patch series includes three improvements for the debug-pagealloc
feature for no-architecture support (!ARCH_SUPPORTS_DEBUG_PAGEALLOC) and
one introduction of the new string library function (memchr_inv).
Akinobu Mita (4):
debug-pagealloc: use plain __ratelimit() instead of
printk_ratelimit()
debug-pagealloc: add support for highmem pages
string: introduce memchr_inv
debug-pagealloc: use memchr_inv
fs/logfs/logfs.h | 1 -
fs/logfs/super.c | 22 --------------
include/linux/string.h | 1 +
lib/string.c | 54 +++++++++++++++++++++++++++++++++++
mm/debug-pagealloc.c | 73 +++++++++++++++++++++++------------------------
mm/slub.c | 47 +-----------------------------
6 files changed, 93 insertions(+), 105 deletions(-)
--
1.7.4.4
--
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^ permalink raw reply [flat|nested] 30+ messages in thread
* [PATCH 1/4] debug-pagealloc: use plain __ratelimit() instead of printk_ratelimit()
2011-08-22 16:29 ` Akinobu Mita
@ 2011-08-22 16:29 ` Akinobu Mita
-1 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-22 16:29 UTC (permalink / raw)
To: linux-kernel, linux-mm, akpm; +Cc: Akinobu Mita
printk_ratelimit() should not be used, because it shares ratelimiting
state with all other unrelated printk_ratelimit() callsites.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
mm/debug-pagealloc.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c
index a1e3324..a4b6d70 100644
--- a/mm/debug-pagealloc.c
+++ b/mm/debug-pagealloc.c
@@ -2,6 +2,7 @@
#include <linux/mm.h>
#include <linux/page-debug-flags.h>
#include <linux/poison.h>
+#include <linux/ratelimit.h>
static inline void set_page_poison(struct page *page)
{
@@ -59,6 +60,7 @@ static bool single_bit_flip(unsigned char a, unsigned char b)
static void check_poison_mem(unsigned char *mem, size_t bytes)
{
+ static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10);
unsigned char *start;
unsigned char *end;
@@ -74,7 +76,7 @@ static void check_poison_mem(unsigned char *mem, size_t bytes)
break;
}
- if (!printk_ratelimit())
+ if (!__ratelimit(&ratelimit))
return;
else if (start == end && single_bit_flip(*start, PAGE_POISON))
printk(KERN_ERR "pagealloc: single bit error\n");
--
1.7.4.4
^ permalink raw reply related [flat|nested] 30+ messages in thread
* [PATCH 1/4] debug-pagealloc: use plain __ratelimit() instead of printk_ratelimit()
@ 2011-08-22 16:29 ` Akinobu Mita
0 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-22 16:29 UTC (permalink / raw)
To: linux-kernel, linux-mm, akpm; +Cc: Akinobu Mita
printk_ratelimit() should not be used, because it shares ratelimiting
state with all other unrelated printk_ratelimit() callsites.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
mm/debug-pagealloc.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c
index a1e3324..a4b6d70 100644
--- a/mm/debug-pagealloc.c
+++ b/mm/debug-pagealloc.c
@@ -2,6 +2,7 @@
#include <linux/mm.h>
#include <linux/page-debug-flags.h>
#include <linux/poison.h>
+#include <linux/ratelimit.h>
static inline void set_page_poison(struct page *page)
{
@@ -59,6 +60,7 @@ static bool single_bit_flip(unsigned char a, unsigned char b)
static void check_poison_mem(unsigned char *mem, size_t bytes)
{
+ static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10);
unsigned char *start;
unsigned char *end;
@@ -74,7 +76,7 @@ static void check_poison_mem(unsigned char *mem, size_t bytes)
break;
}
- if (!printk_ratelimit())
+ if (!__ratelimit(&ratelimit))
return;
else if (start == end && single_bit_flip(*start, PAGE_POISON))
printk(KERN_ERR "pagealloc: single bit error\n");
--
1.7.4.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply related [flat|nested] 30+ messages in thread
* [PATCH 2/4] debug-pagealloc: add support for highmem pages
2011-08-22 16:29 ` Akinobu Mita
@ 2011-08-22 16:29 ` Akinobu Mita
-1 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-22 16:29 UTC (permalink / raw)
To: linux-kernel, linux-mm, akpm; +Cc: Akinobu Mita
This adds support for highmem pages poisoning and verification to the
debug-pagealloc feature for no-architecture support.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
mm/debug-pagealloc.c | 61 ++++++++++++++++++++++++-------------------------
1 files changed, 30 insertions(+), 31 deletions(-)
diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c
index a4b6d70..5afe80c 100644
--- a/mm/debug-pagealloc.c
+++ b/mm/debug-pagealloc.c
@@ -1,5 +1,6 @@
#include <linux/kernel.h>
#include <linux/mm.h>
+#include <linux/highmem.h>
#include <linux/page-debug-flags.h>
#include <linux/poison.h>
#include <linux/ratelimit.h>
@@ -19,28 +20,25 @@ static inline bool page_poison(struct page *page)
return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
}
-static void poison_highpage(struct page *page)
-{
- /*
- * Page poisoning for highmem pages is not implemented.
- *
- * This can be called from interrupt contexts.
- * So we need to create a new kmap_atomic slot for this
- * application and it will need interrupt protection.
- */
-}
-
static void poison_page(struct page *page)
{
void *addr;
-
- if (PageHighMem(page)) {
- poison_highpage(page);
- return;
+ unsigned long flags;
+ bool highmem = PageHighMem(page);
+
+ if (highmem) {
+ local_irq_save(flags);
+ addr = kmap_atomic(page);
+ } else {
+ addr = page_address(page);
}
set_page_poison(page);
- addr = page_address(page);
memset(addr, PAGE_POISON, PAGE_SIZE);
+
+ if (highmem) {
+ kunmap_atomic(addr);
+ local_irq_restore(flags);
+ }
}
static void poison_pages(struct page *page, int n)
@@ -88,26 +86,27 @@ static void check_poison_mem(unsigned char *mem, size_t bytes)
dump_stack();
}
-static void unpoison_highpage(struct page *page)
-{
- /*
- * See comment in poison_highpage().
- * Highmem pages should not be poisoned for now
- */
- BUG_ON(page_poison(page));
-}
-
static void unpoison_page(struct page *page)
{
- if (PageHighMem(page)) {
- unpoison_highpage(page);
+ void *addr;
+ unsigned long flags;
+ bool highmem = PageHighMem(page);
+
+ if (!page_poison(page))
return;
+
+ if (highmem) {
+ local_irq_save(flags);
+ addr = kmap_atomic(page);
+ } else {
+ addr = page_address(page);
}
- if (page_poison(page)) {
- void *addr = page_address(page);
+ check_poison_mem(addr, PAGE_SIZE);
+ clear_page_poison(page);
- check_poison_mem(addr, PAGE_SIZE);
- clear_page_poison(page);
+ if (highmem) {
+ kunmap_atomic(addr);
+ local_irq_restore(flags);
}
}
--
1.7.4.4
^ permalink raw reply related [flat|nested] 30+ messages in thread
* [PATCH 2/4] debug-pagealloc: add support for highmem pages
@ 2011-08-22 16:29 ` Akinobu Mita
0 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-22 16:29 UTC (permalink / raw)
To: linux-kernel, linux-mm, akpm; +Cc: Akinobu Mita
This adds support for highmem pages poisoning and verification to the
debug-pagealloc feature for no-architecture support.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
mm/debug-pagealloc.c | 61 ++++++++++++++++++++++++-------------------------
1 files changed, 30 insertions(+), 31 deletions(-)
diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c
index a4b6d70..5afe80c 100644
--- a/mm/debug-pagealloc.c
+++ b/mm/debug-pagealloc.c
@@ -1,5 +1,6 @@
#include <linux/kernel.h>
#include <linux/mm.h>
+#include <linux/highmem.h>
#include <linux/page-debug-flags.h>
#include <linux/poison.h>
#include <linux/ratelimit.h>
@@ -19,28 +20,25 @@ static inline bool page_poison(struct page *page)
return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
}
-static void poison_highpage(struct page *page)
-{
- /*
- * Page poisoning for highmem pages is not implemented.
- *
- * This can be called from interrupt contexts.
- * So we need to create a new kmap_atomic slot for this
- * application and it will need interrupt protection.
- */
-}
-
static void poison_page(struct page *page)
{
void *addr;
-
- if (PageHighMem(page)) {
- poison_highpage(page);
- return;
+ unsigned long flags;
+ bool highmem = PageHighMem(page);
+
+ if (highmem) {
+ local_irq_save(flags);
+ addr = kmap_atomic(page);
+ } else {
+ addr = page_address(page);
}
set_page_poison(page);
- addr = page_address(page);
memset(addr, PAGE_POISON, PAGE_SIZE);
+
+ if (highmem) {
+ kunmap_atomic(addr);
+ local_irq_restore(flags);
+ }
}
static void poison_pages(struct page *page, int n)
@@ -88,26 +86,27 @@ static void check_poison_mem(unsigned char *mem, size_t bytes)
dump_stack();
}
-static void unpoison_highpage(struct page *page)
-{
- /*
- * See comment in poison_highpage().
- * Highmem pages should not be poisoned for now
- */
- BUG_ON(page_poison(page));
-}
-
static void unpoison_page(struct page *page)
{
- if (PageHighMem(page)) {
- unpoison_highpage(page);
+ void *addr;
+ unsigned long flags;
+ bool highmem = PageHighMem(page);
+
+ if (!page_poison(page))
return;
+
+ if (highmem) {
+ local_irq_save(flags);
+ addr = kmap_atomic(page);
+ } else {
+ addr = page_address(page);
}
- if (page_poison(page)) {
- void *addr = page_address(page);
+ check_poison_mem(addr, PAGE_SIZE);
+ clear_page_poison(page);
- check_poison_mem(addr, PAGE_SIZE);
- clear_page_poison(page);
+ if (highmem) {
+ kunmap_atomic(addr);
+ local_irq_restore(flags);
}
}
--
1.7.4.4
--
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^ permalink raw reply related [flat|nested] 30+ messages in thread
* [PATCH 3/4] string: introduce memchr_inv
2011-08-22 16:29 ` Akinobu Mita
@ 2011-08-22 16:29 ` Akinobu Mita
-1 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-22 16:29 UTC (permalink / raw)
To: linux-kernel, linux-mm, akpm
Cc: Akinobu Mita, Christoph Lameter, Pekka Enberg, Matt Mackall,
Joern Engel, logfs, Marcin Slusarz, Eric Dumazet
memchr_inv() is mainly used to check whether the whole buffer is filled
with just a specified byte.
The function name and prototype are stolen from logfs and the
implementation is from SLUB.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: linux-mm@kvack.org
Cc: Joern Engel <joern@logfs.org>
Cc: logfs@logfs.org
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
---
fs/logfs/logfs.h | 1 -
fs/logfs/super.c | 22 -------------------
include/linux/string.h | 1 +
lib/string.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++
mm/slub.c | 47 +----------------------------------------
5 files changed, 57 insertions(+), 68 deletions(-)
diff --git a/fs/logfs/logfs.h b/fs/logfs/logfs.h
index f22d108..398ecff 100644
--- a/fs/logfs/logfs.h
+++ b/fs/logfs/logfs.h
@@ -618,7 +618,6 @@ static inline int logfs_buf_recover(struct logfs_area *area, u64 ofs,
struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index);
void emergency_read_end(struct page *page);
void logfs_crash_dump(struct super_block *sb);
-void *memchr_inv(const void *s, int c, size_t n);
int logfs_statfs(struct dentry *dentry, struct kstatfs *stats);
int logfs_check_ds(struct logfs_disk_super *ds);
int logfs_write_sb(struct super_block *sb);
diff --git a/fs/logfs/super.c b/fs/logfs/super.c
index ce03a18..f2697e4 100644
--- a/fs/logfs/super.c
+++ b/fs/logfs/super.c
@@ -91,28 +91,6 @@ void logfs_crash_dump(struct super_block *sb)
}
/*
- * TODO: move to lib/string.c
- */
-/**
- * memchr_inv - Find a character in an area of memory.
- * @s: The memory area
- * @c: The byte to search for
- * @n: The size of the area.
- *
- * returns the address of the first character other than @c, or %NULL
- * if the whole buffer contains just @c.
- */
-void *memchr_inv(const void *s, int c, size_t n)
-{
- const unsigned char *p = s;
- while (n-- != 0)
- if ((unsigned char)c != *p++)
- return (void *)(p - 1);
-
- return NULL;
-}
-
-/*
* FIXME: There should be a reserve for root, similar to ext2.
*/
int logfs_statfs(struct dentry *dentry, struct kstatfs *stats)
diff --git a/include/linux/string.h b/include/linux/string.h
index a176db2..e033564 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -114,6 +114,7 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
#ifndef __HAVE_ARCH_MEMCHR
extern void * memchr(const void *,int,__kernel_size_t);
#endif
+void *memchr_inv(const void *s, int c, size_t n);
extern char *kstrdup(const char *s, gfp_t gfp);
extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
diff --git a/lib/string.c b/lib/string.c
index 01fad9b..18f5111 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -756,3 +756,57 @@ void *memchr(const void *s, int c, size_t n)
}
EXPORT_SYMBOL(memchr);
#endif
+
+static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
+{
+ while (bytes) {
+ if (*start != value)
+ return (void *)start;
+ start++;
+ bytes--;
+ }
+ return NULL;
+}
+
+/**
+ * memchr_inv - Find a character in an area of memory.
+ * @s: The memory area
+ * @c: The byte to search for
+ * @n: The size of the area.
+ *
+ * returns the address of the first character other than @c, or %NULL
+ * if the whole buffer contains just @c.
+ */
+void *memchr_inv(const void *start, int c, size_t bytes)
+{
+ u8 value = c;
+ u64 value64;
+ unsigned int words, prefix;
+
+ if (bytes <= 16)
+ return check_bytes8(start, value, bytes);
+
+ value64 = value | value << 8 | value << 16 | value << 24;
+ value64 = (value64 & 0xffffffff) | value64 << 32;
+ prefix = 8 - ((unsigned long)start) % 8;
+
+ if (prefix) {
+ u8 *r = check_bytes8(start, value, prefix);
+ if (r)
+ return r;
+ start += prefix;
+ bytes -= prefix;
+ }
+
+ words = bytes / 8;
+
+ while (words) {
+ if (*(u64 *)start != value64)
+ return check_bytes8(start, value, 8);
+ start += 8;
+ words--;
+ }
+
+ return check_bytes8(start, value, bytes % 8);
+}
+EXPORT_SYMBOL(memchr_inv);
diff --git a/mm/slub.c b/mm/slub.c
index 9f662d7..692fe34 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -681,49 +681,6 @@ static void init_object(struct kmem_cache *s, void *object, u8 val)
memset(p + s->objsize, val, s->inuse - s->objsize);
}
-static u8 *check_bytes8(u8 *start, u8 value, unsigned int bytes)
-{
- while (bytes) {
- if (*start != value)
- return start;
- start++;
- bytes--;
- }
- return NULL;
-}
-
-static u8 *check_bytes(u8 *start, u8 value, unsigned int bytes)
-{
- u64 value64;
- unsigned int words, prefix;
-
- if (bytes <= 16)
- return check_bytes8(start, value, bytes);
-
- value64 = value | value << 8 | value << 16 | value << 24;
- value64 = (value64 & 0xffffffff) | value64 << 32;
- prefix = 8 - ((unsigned long)start) % 8;
-
- if (prefix) {
- u8 *r = check_bytes8(start, value, prefix);
- if (r)
- return r;
- start += prefix;
- bytes -= prefix;
- }
-
- words = bytes / 8;
-
- while (words) {
- if (*(u64 *)start != value64)
- return check_bytes8(start, value, 8);
- start += 8;
- words--;
- }
-
- return check_bytes8(start, value, bytes % 8);
-}
-
static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
void *from, void *to)
{
@@ -738,7 +695,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
u8 *fault;
u8 *end;
- fault = check_bytes(start, value, bytes);
+ fault = memchr_inv(start, value, bytes);
if (!fault)
return 1;
@@ -831,7 +788,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
if (!remainder)
return 1;
- fault = check_bytes(end - remainder, POISON_INUSE, remainder);
+ fault = memchr_inv(end - remainder, POISON_INUSE, remainder);
if (!fault)
return 1;
while (end > fault && end[-1] == POISON_INUSE)
--
1.7.4.4
^ permalink raw reply related [flat|nested] 30+ messages in thread
* [PATCH 3/4] string: introduce memchr_inv
@ 2011-08-22 16:29 ` Akinobu Mita
0 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-22 16:29 UTC (permalink / raw)
To: linux-kernel, linux-mm, akpm
Cc: Akinobu Mita, Christoph Lameter, Pekka Enberg, Matt Mackall,
Joern Engel, logfs, Marcin Slusarz, Eric Dumazet
memchr_inv() is mainly used to check whether the whole buffer is filled
with just a specified byte.
The function name and prototype are stolen from logfs and the
implementation is from SLUB.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: linux-mm@kvack.org
Cc: Joern Engel <joern@logfs.org>
Cc: logfs@logfs.org
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
---
fs/logfs/logfs.h | 1 -
fs/logfs/super.c | 22 -------------------
include/linux/string.h | 1 +
lib/string.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++
mm/slub.c | 47 +----------------------------------------
5 files changed, 57 insertions(+), 68 deletions(-)
diff --git a/fs/logfs/logfs.h b/fs/logfs/logfs.h
index f22d108..398ecff 100644
--- a/fs/logfs/logfs.h
+++ b/fs/logfs/logfs.h
@@ -618,7 +618,6 @@ static inline int logfs_buf_recover(struct logfs_area *area, u64 ofs,
struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index);
void emergency_read_end(struct page *page);
void logfs_crash_dump(struct super_block *sb);
-void *memchr_inv(const void *s, int c, size_t n);
int logfs_statfs(struct dentry *dentry, struct kstatfs *stats);
int logfs_check_ds(struct logfs_disk_super *ds);
int logfs_write_sb(struct super_block *sb);
diff --git a/fs/logfs/super.c b/fs/logfs/super.c
index ce03a18..f2697e4 100644
--- a/fs/logfs/super.c
+++ b/fs/logfs/super.c
@@ -91,28 +91,6 @@ void logfs_crash_dump(struct super_block *sb)
}
/*
- * TODO: move to lib/string.c
- */
-/**
- * memchr_inv - Find a character in an area of memory.
- * @s: The memory area
- * @c: The byte to search for
- * @n: The size of the area.
- *
- * returns the address of the first character other than @c, or %NULL
- * if the whole buffer contains just @c.
- */
-void *memchr_inv(const void *s, int c, size_t n)
-{
- const unsigned char *p = s;
- while (n-- != 0)
- if ((unsigned char)c != *p++)
- return (void *)(p - 1);
-
- return NULL;
-}
-
-/*
* FIXME: There should be a reserve for root, similar to ext2.
*/
int logfs_statfs(struct dentry *dentry, struct kstatfs *stats)
diff --git a/include/linux/string.h b/include/linux/string.h
index a176db2..e033564 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -114,6 +114,7 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
#ifndef __HAVE_ARCH_MEMCHR
extern void * memchr(const void *,int,__kernel_size_t);
#endif
+void *memchr_inv(const void *s, int c, size_t n);
extern char *kstrdup(const char *s, gfp_t gfp);
extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
diff --git a/lib/string.c b/lib/string.c
index 01fad9b..18f5111 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -756,3 +756,57 @@ void *memchr(const void *s, int c, size_t n)
}
EXPORT_SYMBOL(memchr);
#endif
+
+static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
+{
+ while (bytes) {
+ if (*start != value)
+ return (void *)start;
+ start++;
+ bytes--;
+ }
+ return NULL;
+}
+
+/**
+ * memchr_inv - Find a character in an area of memory.
+ * @s: The memory area
+ * @c: The byte to search for
+ * @n: The size of the area.
+ *
+ * returns the address of the first character other than @c, or %NULL
+ * if the whole buffer contains just @c.
+ */
+void *memchr_inv(const void *start, int c, size_t bytes)
+{
+ u8 value = c;
+ u64 value64;
+ unsigned int words, prefix;
+
+ if (bytes <= 16)
+ return check_bytes8(start, value, bytes);
+
+ value64 = value | value << 8 | value << 16 | value << 24;
+ value64 = (value64 & 0xffffffff) | value64 << 32;
+ prefix = 8 - ((unsigned long)start) % 8;
+
+ if (prefix) {
+ u8 *r = check_bytes8(start, value, prefix);
+ if (r)
+ return r;
+ start += prefix;
+ bytes -= prefix;
+ }
+
+ words = bytes / 8;
+
+ while (words) {
+ if (*(u64 *)start != value64)
+ return check_bytes8(start, value, 8);
+ start += 8;
+ words--;
+ }
+
+ return check_bytes8(start, value, bytes % 8);
+}
+EXPORT_SYMBOL(memchr_inv);
diff --git a/mm/slub.c b/mm/slub.c
index 9f662d7..692fe34 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -681,49 +681,6 @@ static void init_object(struct kmem_cache *s, void *object, u8 val)
memset(p + s->objsize, val, s->inuse - s->objsize);
}
-static u8 *check_bytes8(u8 *start, u8 value, unsigned int bytes)
-{
- while (bytes) {
- if (*start != value)
- return start;
- start++;
- bytes--;
- }
- return NULL;
-}
-
-static u8 *check_bytes(u8 *start, u8 value, unsigned int bytes)
-{
- u64 value64;
- unsigned int words, prefix;
-
- if (bytes <= 16)
- return check_bytes8(start, value, bytes);
-
- value64 = value | value << 8 | value << 16 | value << 24;
- value64 = (value64 & 0xffffffff) | value64 << 32;
- prefix = 8 - ((unsigned long)start) % 8;
-
- if (prefix) {
- u8 *r = check_bytes8(start, value, prefix);
- if (r)
- return r;
- start += prefix;
- bytes -= prefix;
- }
-
- words = bytes / 8;
-
- while (words) {
- if (*(u64 *)start != value64)
- return check_bytes8(start, value, 8);
- start += 8;
- words--;
- }
-
- return check_bytes8(start, value, bytes % 8);
-}
-
static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
void *from, void *to)
{
@@ -738,7 +695,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
u8 *fault;
u8 *end;
- fault = check_bytes(start, value, bytes);
+ fault = memchr_inv(start, value, bytes);
if (!fault)
return 1;
@@ -831,7 +788,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
if (!remainder)
return 1;
- fault = check_bytes(end - remainder, POISON_INUSE, remainder);
+ fault = memchr_inv(end - remainder, POISON_INUSE, remainder);
if (!fault)
return 1;
while (end > fault && end[-1] == POISON_INUSE)
--
1.7.4.4
--
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^ permalink raw reply related [flat|nested] 30+ messages in thread
* [PATCH 4/4] debug-pagealloc: use memchr_inv
2011-08-22 16:29 ` Akinobu Mita
@ 2011-08-22 16:29 ` Akinobu Mita
-1 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-22 16:29 UTC (permalink / raw)
To: linux-kernel, linux-mm, akpm; +Cc: Akinobu Mita
Use newly introduced memchr_inv for page verification.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
mm/debug-pagealloc.c | 8 +++-----
1 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c
index 5afe80c..d8470d4 100644
--- a/mm/debug-pagealloc.c
+++ b/mm/debug-pagealloc.c
@@ -1,4 +1,5 @@
#include <linux/kernel.h>
+#include <linux/string.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/page-debug-flags.h>
@@ -62,11 +63,8 @@ static void check_poison_mem(unsigned char *mem, size_t bytes)
unsigned char *start;
unsigned char *end;
- for (start = mem; start < mem + bytes; start++) {
- if (*start != PAGE_POISON)
- break;
- }
- if (start == mem + bytes)
+ start = memchr_inv(mem, PAGE_POISON, bytes);
+ if (!start)
return;
for (end = mem + bytes - 1; end > start; end--) {
--
1.7.4.4
^ permalink raw reply related [flat|nested] 30+ messages in thread
* [PATCH 4/4] debug-pagealloc: use memchr_inv
@ 2011-08-22 16:29 ` Akinobu Mita
0 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-22 16:29 UTC (permalink / raw)
To: linux-kernel, linux-mm, akpm; +Cc: Akinobu Mita
Use newly introduced memchr_inv for page verification.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
mm/debug-pagealloc.c | 8 +++-----
1 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c
index 5afe80c..d8470d4 100644
--- a/mm/debug-pagealloc.c
+++ b/mm/debug-pagealloc.c
@@ -1,4 +1,5 @@
#include <linux/kernel.h>
+#include <linux/string.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/page-debug-flags.h>
@@ -62,11 +63,8 @@ static void check_poison_mem(unsigned char *mem, size_t bytes)
unsigned char *start;
unsigned char *end;
- for (start = mem; start < mem + bytes; start++) {
- if (*start != PAGE_POISON)
- break;
- }
- if (start == mem + bytes)
+ start = memchr_inv(mem, PAGE_POISON, bytes);
+ if (!start)
return;
for (end = mem + bytes - 1; end > start; end--) {
--
1.7.4.4
--
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the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply related [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
2011-08-22 16:29 ` Akinobu Mita
@ 2011-08-22 16:57 ` Pekka Enberg
-1 siblings, 0 replies; 30+ messages in thread
From: Pekka Enberg @ 2011-08-22 16:57 UTC (permalink / raw)
To: Akinobu Mita
Cc: linux-kernel, linux-mm, akpm, Christoph Lameter, Matt Mackall,
Joern Engel, logfs, Marcin Slusarz, Eric Dumazet
On Tue, 2011-08-23 at 01:29 +0900, Akinobu Mita wrote:
> memchr_inv() is mainly used to check whether the whole buffer is filled
> with just a specified byte.
>
> The function name and prototype are stolen from logfs and the
> implementation is from SLUB.
>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> Cc: Christoph Lameter <cl@linux-foundation.org>
> Cc: Pekka Enberg <penberg@kernel.org>
> Cc: Matt Mackall <mpm@selenic.com>
> Cc: linux-mm@kvack.org
> Cc: Joern Engel <joern@logfs.org>
> Cc: logfs@logfs.org
> Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
> Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
@ 2011-08-22 16:57 ` Pekka Enberg
0 siblings, 0 replies; 30+ messages in thread
From: Pekka Enberg @ 2011-08-22 16:57 UTC (permalink / raw)
To: Akinobu Mita
Cc: linux-kernel, linux-mm, akpm, Christoph Lameter, Matt Mackall,
Joern Engel, logfs, Marcin Slusarz, Eric Dumazet
On Tue, 2011-08-23 at 01:29 +0900, Akinobu Mita wrote:
> memchr_inv() is mainly used to check whether the whole buffer is filled
> with just a specified byte.
>
> The function name and prototype are stolen from logfs and the
> implementation is from SLUB.
>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> Cc: Christoph Lameter <cl@linux-foundation.org>
> Cc: Pekka Enberg <penberg@kernel.org>
> Cc: Matt Mackall <mpm@selenic.com>
> Cc: linux-mm@kvack.org
> Cc: Joern Engel <joern@logfs.org>
> Cc: logfs@logfs.org
> Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
> Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
2011-08-22 16:57 ` Pekka Enberg
@ 2011-08-22 17:09 ` Jörn Engel
-1 siblings, 0 replies; 30+ messages in thread
From: Jörn Engel @ 2011-08-22 17:09 UTC (permalink / raw)
To: Pekka Enberg
Cc: Akinobu Mita, linux-kernel, linux-mm, akpm, Christoph Lameter,
Matt Mackall, logfs, Marcin Slusarz, Eric Dumazet
On Mon, 22 August 2011 19:57:50 +0300, Pekka Enberg wrote:
> On Tue, 2011-08-23 at 01:29 +0900, Akinobu Mita wrote:
> > memchr_inv() is mainly used to check whether the whole buffer is filled
> > with just a specified byte.
> >
> > The function name and prototype are stolen from logfs and the
> > implementation is from SLUB.
> >
> > Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> > Cc: Christoph Lameter <cl@linux-foundation.org>
> > Cc: Pekka Enberg <penberg@kernel.org>
> > Cc: Matt Mackall <mpm@selenic.com>
> > Cc: linux-mm@kvack.org
> > Cc: Joern Engel <joern@logfs.org>
> > Cc: logfs@logfs.org
> > Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
> > Cc: Eric Dumazet <eric.dumazet@gmail.com>
>
> Acked-by: Pekka Enberg <penberg@kernel.org>
Acked-by: Joern Engel <joern@logfs.org>
Jörn
--
He who knows that enough is enough will always have enough.
-- Lao Tsu
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
@ 2011-08-22 17:09 ` Jörn Engel
0 siblings, 0 replies; 30+ messages in thread
From: Jörn Engel @ 2011-08-22 17:09 UTC (permalink / raw)
To: Pekka Enberg
Cc: Akinobu Mita, linux-kernel, linux-mm, akpm, Christoph Lameter,
Matt Mackall, logfs, Marcin Slusarz, Eric Dumazet
On Mon, 22 August 2011 19:57:50 +0300, Pekka Enberg wrote:
> On Tue, 2011-08-23 at 01:29 +0900, Akinobu Mita wrote:
> > memchr_inv() is mainly used to check whether the whole buffer is filled
> > with just a specified byte.
> >
> > The function name and prototype are stolen from logfs and the
> > implementation is from SLUB.
> >
> > Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> > Cc: Christoph Lameter <cl@linux-foundation.org>
> > Cc: Pekka Enberg <penberg@kernel.org>
> > Cc: Matt Mackall <mpm@selenic.com>
> > Cc: linux-mm@kvack.org
> > Cc: Joern Engel <joern@logfs.org>
> > Cc: logfs@logfs.org
> > Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
> > Cc: Eric Dumazet <eric.dumazet@gmail.com>
>
> Acked-by: Pekka Enberg <penberg@kernel.org>
Acked-by: Joern Engel <joern@logfs.org>
JA?rn
--
He who knows that enough is enough will always have enough.
-- Lao Tsu
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 2/4] debug-pagealloc: add support for highmem pages
2011-08-22 16:29 ` Akinobu Mita
@ 2011-08-22 20:43 ` Andrew Morton
-1 siblings, 0 replies; 30+ messages in thread
From: Andrew Morton @ 2011-08-22 20:43 UTC (permalink / raw)
To: Akinobu Mita; +Cc: linux-kernel, linux-mm
On Tue, 23 Aug 2011 01:29:06 +0900
Akinobu Mita <akinobu.mita@gmail.com> wrote:
> This adds support for highmem pages poisoning and verification to the
> debug-pagealloc feature for no-architecture support.
>
> ...
>
> static void poison_page(struct page *page)
> {
> void *addr;
> -
> - if (PageHighMem(page)) {
> - poison_highpage(page);
> - return;
> + unsigned long flags;
> + bool highmem = PageHighMem(page);
> +
> + if (highmem) {
> + local_irq_save(flags);
> + addr = kmap_atomic(page);
> + } else {
> + addr = page_address(page);
> }
> set_page_poison(page);
> - addr = page_address(page);
> memset(addr, PAGE_POISON, PAGE_SIZE);
> +
> + if (highmem) {
> + kunmap_atomic(addr);
> + local_irq_restore(flags);
> + }
> }
This seems more complicated than is needed. Couldn't we just do
static void poison_page(struct page *page)
{
void *addr;
preempt_disable();
addr = kmap_atomic(page);
set_page_poison(page);
memset(addr, PAGE_POISON, PAGE_SIZE);
kunmap_atomic(addr);
preempt_enable();
}
?
> + addr = kmap_atomic(page);
That reminds me - we need to convert every "kmap_atomic(p, foo)" to
"kmap_atomic(p)" then remove the kmap_atomic back-compatibility macro.
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 2/4] debug-pagealloc: add support for highmem pages
@ 2011-08-22 20:43 ` Andrew Morton
0 siblings, 0 replies; 30+ messages in thread
From: Andrew Morton @ 2011-08-22 20:43 UTC (permalink / raw)
To: Akinobu Mita; +Cc: linux-kernel, linux-mm
On Tue, 23 Aug 2011 01:29:06 +0900
Akinobu Mita <akinobu.mita@gmail.com> wrote:
> This adds support for highmem pages poisoning and verification to the
> debug-pagealloc feature for no-architecture support.
>
> ...
>
> static void poison_page(struct page *page)
> {
> void *addr;
> -
> - if (PageHighMem(page)) {
> - poison_highpage(page);
> - return;
> + unsigned long flags;
> + bool highmem = PageHighMem(page);
> +
> + if (highmem) {
> + local_irq_save(flags);
> + addr = kmap_atomic(page);
> + } else {
> + addr = page_address(page);
> }
> set_page_poison(page);
> - addr = page_address(page);
> memset(addr, PAGE_POISON, PAGE_SIZE);
> +
> + if (highmem) {
> + kunmap_atomic(addr);
> + local_irq_restore(flags);
> + }
> }
This seems more complicated than is needed. Couldn't we just do
static void poison_page(struct page *page)
{
void *addr;
preempt_disable();
addr = kmap_atomic(page);
set_page_poison(page);
memset(addr, PAGE_POISON, PAGE_SIZE);
kunmap_atomic(addr);
preempt_enable();
}
?
> + addr = kmap_atomic(page);
That reminds me - we need to convert every "kmap_atomic(p, foo)" to
"kmap_atomic(p)" then remove the kmap_atomic back-compatibility macro.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
2011-08-22 16:29 ` Akinobu Mita
@ 2011-08-22 20:52 ` Andrew Morton
-1 siblings, 0 replies; 30+ messages in thread
From: Andrew Morton @ 2011-08-22 20:52 UTC (permalink / raw)
To: Akinobu Mita
Cc: linux-kernel, linux-mm, Christoph Lameter, Pekka Enberg,
Matt Mackall, Joern Engel, logfs, Marcin Slusarz, Eric Dumazet,
linux-arch
On Tue, 23 Aug 2011 01:29:07 +0900
Akinobu Mita <akinobu.mita@gmail.com> wrote:
> memchr_inv() is mainly used to check whether the whole buffer is filled
> with just a specified byte.
>
> The function name and prototype are stolen from logfs and the
> implementation is from SLUB.
>
> ...
>
> +/**
> + * memchr_inv - Find a character in an area of memory.
> + * @s: The memory area
> + * @c: The byte to search for
> + * @n: The size of the area.
This text seems to be stolen from memchr(). I guess it's close enough.
> + * returns the address of the first character other than @c, or %NULL
> + * if the whole buffer contains just @c.
> + */
> +void *memchr_inv(const void *start, int c, size_t bytes)
> +{
> + u8 value = c;
> + u64 value64;
> + unsigned int words, prefix;
> +
> + if (bytes <= 16)
> + return check_bytes8(start, value, bytes);
> +
> + value64 = value | value << 8 | value << 16 | value << 24;
> + value64 = (value64 & 0xffffffff) | value64 << 32;
> + prefix = 8 - ((unsigned long)start) % 8;
> +
> + if (prefix) {
> + u8 *r = check_bytes8(start, value, prefix);
> + if (r)
> + return r;
> + start += prefix;
> + bytes -= prefix;
> + }
> +
> + words = bytes / 8;
> +
> + while (words) {
> + if (*(u64 *)start != value64)
OK, problem. This will explode if passed a misaligned address on
certain (non-x86) architectures. This is nasty because people will
develop and test code on x86 and it works. Much later, the
alpha/ia64/etc guys discover the problem.
One fix would be to use get_unaligned(). This might be slow on some
architectures, I don't know. Another fix is to restrict the caller's
alignment freedom; document this and add a runtime WARN_ON().
> + return check_bytes8(start, value, 8);
> + start += 8;
> + words--;
> + }
> +
> + return check_bytes8(start, value, bytes % 8);
> +}
> +EXPORT_SYMBOL(memchr_inv);
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
@ 2011-08-22 20:52 ` Andrew Morton
0 siblings, 0 replies; 30+ messages in thread
From: Andrew Morton @ 2011-08-22 20:52 UTC (permalink / raw)
To: Akinobu Mita
Cc: linux-kernel, linux-mm, Christoph Lameter, Pekka Enberg,
Matt Mackall, Joern Engel, logfs, Marcin Slusarz, Eric Dumazet,
linux-arch
On Tue, 23 Aug 2011 01:29:07 +0900
Akinobu Mita <akinobu.mita@gmail.com> wrote:
> memchr_inv() is mainly used to check whether the whole buffer is filled
> with just a specified byte.
>
> The function name and prototype are stolen from logfs and the
> implementation is from SLUB.
>
> ...
>
> +/**
> + * memchr_inv - Find a character in an area of memory.
> + * @s: The memory area
> + * @c: The byte to search for
> + * @n: The size of the area.
This text seems to be stolen from memchr(). I guess it's close enough.
> + * returns the address of the first character other than @c, or %NULL
> + * if the whole buffer contains just @c.
> + */
> +void *memchr_inv(const void *start, int c, size_t bytes)
> +{
> + u8 value = c;
> + u64 value64;
> + unsigned int words, prefix;
> +
> + if (bytes <= 16)
> + return check_bytes8(start, value, bytes);
> +
> + value64 = value | value << 8 | value << 16 | value << 24;
> + value64 = (value64 & 0xffffffff) | value64 << 32;
> + prefix = 8 - ((unsigned long)start) % 8;
> +
> + if (prefix) {
> + u8 *r = check_bytes8(start, value, prefix);
> + if (r)
> + return r;
> + start += prefix;
> + bytes -= prefix;
> + }
> +
> + words = bytes / 8;
> +
> + while (words) {
> + if (*(u64 *)start != value64)
OK, problem. This will explode if passed a misaligned address on
certain (non-x86) architectures. This is nasty because people will
develop and test code on x86 and it works. Much later, the
alpha/ia64/etc guys discover the problem.
One fix would be to use get_unaligned(). This might be slow on some
architectures, I don't know. Another fix is to restrict the caller's
alignment freedom; document this and add a runtime WARN_ON().
> + return check_bytes8(start, value, 8);
> + start += 8;
> + words--;
> + }
> +
> + return check_bytes8(start, value, bytes % 8);
> +}
> +EXPORT_SYMBOL(memchr_inv);
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
2011-08-22 16:29 ` Akinobu Mita
@ 2011-08-22 20:59 ` Geert Uytterhoeven
-1 siblings, 0 replies; 30+ messages in thread
From: Geert Uytterhoeven @ 2011-08-22 20:59 UTC (permalink / raw)
To: Akinobu Mita
Cc: linux-kernel, linux-mm, akpm, Christoph Lameter, Pekka Enberg,
Matt Mackall, Joern Engel, logfs, Marcin Slusarz, Eric Dumazet
On Mon, Aug 22, 2011 at 18:29, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> +/**
> + * memchr_inv - Find a character in an area of memory.
This description doesn't really match.
> + * @s: The memory area
> + * @c: The byte to search for
> + * @n: The size of the area.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
@ 2011-08-22 20:59 ` Geert Uytterhoeven
0 siblings, 0 replies; 30+ messages in thread
From: Geert Uytterhoeven @ 2011-08-22 20:59 UTC (permalink / raw)
To: Akinobu Mita
Cc: linux-kernel, linux-mm, akpm, Christoph Lameter, Pekka Enberg,
Matt Mackall, Joern Engel, logfs, Marcin Slusarz, Eric Dumazet
On Mon, Aug 22, 2011 at 18:29, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> +/**
> + * memchr_inv - Find a character in an area of memory.
This description doesn't really match.
> + * @s: The memory area
> + * @c: The byte to search for
> + * @n: The size of the area.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
2011-08-22 20:52 ` Andrew Morton
@ 2011-08-22 21:50 ` Andrew Morton
-1 siblings, 0 replies; 30+ messages in thread
From: Andrew Morton @ 2011-08-22 21:50 UTC (permalink / raw)
To: Akinobu Mita, linux-kernel, linux-mm, Christoph Lameter,
Pekka Enberg, Matt Mackall, Joern Engel, logfs, Marcin Slusarz,
Eric Dumazet, linux-arch
On Mon, 22 Aug 2011 13:52:18 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:
> > + value64 = value | value << 8 | value << 16 | value << 24;
> > + value64 = (value64 & 0xffffffff) | value64 << 32;
> > + prefix = 8 - ((unsigned long)start) % 8;
> > +
> > + if (prefix) {
> > + u8 *r = check_bytes8(start, value, prefix);
> > + if (r)
> > + return r;
> > + start += prefix;
> > + bytes -= prefix;
> > + }
> > +
> > + words = bytes / 8;
> > +
> > + while (words) {
> > + if (*(u64 *)start != value64)
>
> OK, problem. This will explode if passed a misaligned address on
> certain (non-x86) architectures.
pls ignore. As Marcin points out, I can't read.
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
2011-08-22 20:52 ` Andrew Morton
(?)
@ 2011-08-22 21:50 ` Andrew Morton
-1 siblings, 0 replies; 30+ messages in thread
From: Andrew Morton @ 2011-08-22 21:50 UTC (permalink / raw)
To: Akinobu Mita, linux-kernel, linux-mm, Christoph Lameter,
Pekka Enberg, Matt
On Mon, 22 Aug 2011 13:52:18 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:
> > + value64 = value | value << 8 | value << 16 | value << 24;
> > + value64 = (value64 & 0xffffffff) | value64 << 32;
> > + prefix = 8 - ((unsigned long)start) % 8;
> > +
> > + if (prefix) {
> > + u8 *r = check_bytes8(start, value, prefix);
> > + if (r)
> > + return r;
> > + start += prefix;
> > + bytes -= prefix;
> > + }
> > +
> > + words = bytes / 8;
> > +
> > + while (words) {
> > + if (*(u64 *)start != value64)
>
> OK, problem. This will explode if passed a misaligned address on
> certain (non-x86) architectures.
pls ignore. As Marcin points out, I can't read.
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
@ 2011-08-22 21:50 ` Andrew Morton
0 siblings, 0 replies; 30+ messages in thread
From: Andrew Morton @ 2011-08-22 21:50 UTC (permalink / raw)
To: Akinobu Mita, linux-kernel, linux-mm, Christoph Lameter,
Pekka Enberg, Matt Mackall, Joern Engel, logfs, Marcin Slusarz,
Eric Dumazet, linux-arch
On Mon, 22 Aug 2011 13:52:18 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:
> > + value64 = value | value << 8 | value << 16 | value << 24;
> > + value64 = (value64 & 0xffffffff) | value64 << 32;
> > + prefix = 8 - ((unsigned long)start) % 8;
> > +
> > + if (prefix) {
> > + u8 *r = check_bytes8(start, value, prefix);
> > + if (r)
> > + return r;
> > + start += prefix;
> > + bytes -= prefix;
> > + }
> > +
> > + words = bytes / 8;
> > +
> > + while (words) {
> > + if (*(u64 *)start != value64)
>
> OK, problem. This will explode if passed a misaligned address on
> certain (non-x86) architectures.
pls ignore. As Marcin points out, I can't read.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
2011-08-22 20:52 ` Andrew Morton
(?)
@ 2011-08-22 21:56 ` Eric Dumazet
-1 siblings, 0 replies; 30+ messages in thread
From: Eric Dumazet @ 2011-08-22 21:56 UTC (permalink / raw)
To: Andrew Morton
Cc: Akinobu Mita, linux-kernel, linux-mm, Christoph Lameter,
Pekka Enberg, Matt Mackall, Joern Engel, logfs, Marcin Slusarz,
linux-arch
Le lundi 22 août 2011 à 13:52 -0700, Andrew Morton a écrit :
> On Tue, 23 Aug 2011 01:29:07 +0900
> Akinobu Mita <akinobu.mita@gmail.com> wrote:
>
> > memchr_inv() is mainly used to check whether the whole buffer is filled
> > with just a specified byte.
> >
> > The function name and prototype are stolen from logfs and the
> > implementation is from SLUB.
> >
> > ...
> >
> > +/**
> > + * memchr_inv - Find a character in an area of memory.
> > + * @s: The memory area
> > + * @c: The byte to search for
> > + * @n: The size of the area.
>
> This text seems to be stolen from memchr(). I guess it's close enough.
>
> > + * returns the address of the first character other than @c, or %NULL
> > + * if the whole buffer contains just @c.
> > + */
> > +void *memchr_inv(const void *start, int c, size_t bytes)
> > +{
> > + u8 value = c;
> > + u64 value64;
> > + unsigned int words, prefix;
> > +
> > + if (bytes <= 16)
> > + return check_bytes8(start, value, bytes);
> > +
> > + value64 = value | value << 8 | value << 16 | value << 24;
> > + value64 = (value64 & 0xffffffff) | value64 << 32;
> > + prefix = 8 - ((unsigned long)start) % 8;
> > +
<snip>
> > + if (prefix) {
> > + u8 *r = check_bytes8(start, value, prefix);
> > + if (r)
> > + return r;
> > + start += prefix;
> > + bytes -= prefix;
> > + }
</snip>
Please note Andrew the previous code just make sure 'start' is aligned
on 8 bytes boundary. (It is suboptimal because if 'start' was already
aligned, we call the slow check_bytes(start, value, 8))
Code should probably do
prefix = (unsigned long)start % 8;
if (prefix) {
prefix = 8 - prefix;
r = check_bytes8(start, value, prefix);
...
> > +
> > + words = bytes / 8;
> > +
> > + while (words) {
> > + if (*(u64 *)start != value64)
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
@ 2011-08-22 21:56 ` Eric Dumazet
0 siblings, 0 replies; 30+ messages in thread
From: Eric Dumazet @ 2011-08-22 21:56 UTC (permalink / raw)
To: Andrew Morton
Cc: Akinobu Mita, linux-kernel, linux-mm, Christoph Lameter,
Pekka Enberg, Matt Mackall, Joern Engel, logfs, Marcin Slusarz,
linux-arch
Le lundi 22 août 2011 à 13:52 -0700, Andrew Morton a écrit :
> On Tue, 23 Aug 2011 01:29:07 +0900
> Akinobu Mita <akinobu.mita@gmail.com> wrote:
>
> > memchr_inv() is mainly used to check whether the whole buffer is filled
> > with just a specified byte.
> >
> > The function name and prototype are stolen from logfs and the
> > implementation is from SLUB.
> >
> > ...
> >
> > +/**
> > + * memchr_inv - Find a character in an area of memory.
> > + * @s: The memory area
> > + * @c: The byte to search for
> > + * @n: The size of the area.
>
> This text seems to be stolen from memchr(). I guess it's close enough.
>
> > + * returns the address of the first character other than @c, or %NULL
> > + * if the whole buffer contains just @c.
> > + */
> > +void *memchr_inv(const void *start, int c, size_t bytes)
> > +{
> > + u8 value = c;
> > + u64 value64;
> > + unsigned int words, prefix;
> > +
> > + if (bytes <= 16)
> > + return check_bytes8(start, value, bytes);
> > +
> > + value64 = value | value << 8 | value << 16 | value << 24;
> > + value64 = (value64 & 0xffffffff) | value64 << 32;
> > + prefix = 8 - ((unsigned long)start) % 8;
> > +
<snip>
> > + if (prefix) {
> > + u8 *r = check_bytes8(start, value, prefix);
> > + if (r)
> > + return r;
> > + start += prefix;
> > + bytes -= prefix;
> > + }
</snip>
Please note Andrew the previous code just make sure 'start' is aligned
on 8 bytes boundary. (It is suboptimal because if 'start' was already
aligned, we call the slow check_bytes(start, value, 8))
Code should probably do
prefix = (unsigned long)start % 8;
if (prefix) {
prefix = 8 - prefix;
r = check_bytes8(start, value, prefix);
...
> > +
> > + words = bytes / 8;
> > +
> > + while (words) {
> > + if (*(u64 *)start != value64)
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
@ 2011-08-22 21:56 ` Eric Dumazet
0 siblings, 0 replies; 30+ messages in thread
From: Eric Dumazet @ 2011-08-22 21:56 UTC (permalink / raw)
To: Andrew Morton
Cc: Akinobu Mita, linux-kernel, linux-mm, Christoph Lameter,
Pekka Enberg, Matt Mackall, Joern Engel, logfs, Marcin Slusarz,
linux-arch
Le lundi 22 aoA>>t 2011 A 13:52 -0700, Andrew Morton a A(C)crit :
> On Tue, 23 Aug 2011 01:29:07 +0900
> Akinobu Mita <akinobu.mita@gmail.com> wrote:
>
> > memchr_inv() is mainly used to check whether the whole buffer is filled
> > with just a specified byte.
> >
> > The function name and prototype are stolen from logfs and the
> > implementation is from SLUB.
> >
> > ...
> >
> > +/**
> > + * memchr_inv - Find a character in an area of memory.
> > + * @s: The memory area
> > + * @c: The byte to search for
> > + * @n: The size of the area.
>
> This text seems to be stolen from memchr(). I guess it's close enough.
>
> > + * returns the address of the first character other than @c, or %NULL
> > + * if the whole buffer contains just @c.
> > + */
> > +void *memchr_inv(const void *start, int c, size_t bytes)
> > +{
> > + u8 value = c;
> > + u64 value64;
> > + unsigned int words, prefix;
> > +
> > + if (bytes <= 16)
> > + return check_bytes8(start, value, bytes);
> > +
> > + value64 = value | value << 8 | value << 16 | value << 24;
> > + value64 = (value64 & 0xffffffff) | value64 << 32;
> > + prefix = 8 - ((unsigned long)start) % 8;
> > +
<snip>
> > + if (prefix) {
> > + u8 *r = check_bytes8(start, value, prefix);
> > + if (r)
> > + return r;
> > + start += prefix;
> > + bytes -= prefix;
> > + }
</snip>
Please note Andrew the previous code just make sure 'start' is aligned
on 8 bytes boundary. (It is suboptimal because if 'start' was already
aligned, we call the slow check_bytes(start, value, 8))
Code should probably do
prefix = (unsigned long)start % 8;
if (prefix) {
prefix = 8 - prefix;
r = check_bytes8(start, value, prefix);
...
> > +
> > + words = bytes / 8;
> > +
> > + while (words) {
> > + if (*(u64 *)start != value64)
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
2011-08-22 20:59 ` Geert Uytterhoeven
@ 2011-08-23 14:31 ` Christoph Lameter
-1 siblings, 0 replies; 30+ messages in thread
From: Christoph Lameter @ 2011-08-23 14:31 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Akinobu Mita, linux-kernel, linux-mm, akpm, Pekka Enberg,
Matt Mackall, Joern Engel, logfs, Marcin Slusarz, Eric Dumazet
On Mon, 22 Aug 2011, Geert Uytterhoeven wrote:
> On Mon, Aug 22, 2011 at 18:29, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> > +/**
> > + * memchr_inv - Find a character in an area of memory.
>
> This description doesn't really match.
Seconded. If you fix that then
Acked-by: Christoph Lameter <cl@linux.com>
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 3/4] string: introduce memchr_inv
@ 2011-08-23 14:31 ` Christoph Lameter
0 siblings, 0 replies; 30+ messages in thread
From: Christoph Lameter @ 2011-08-23 14:31 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Akinobu Mita, linux-kernel, linux-mm, akpm, Pekka Enberg,
Matt Mackall, Joern Engel, logfs, Marcin Slusarz, Eric Dumazet
On Mon, 22 Aug 2011, Geert Uytterhoeven wrote:
> On Mon, Aug 22, 2011 at 18:29, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> > +/**
> > + * memchr_inv - Find a character in an area of memory.
>
> This description doesn't really match.
Seconded. If you fix that then
Acked-by: Christoph Lameter <cl@linux.com>
--
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^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 2/4] debug-pagealloc: add support for highmem pages
2011-08-22 20:43 ` Andrew Morton
@ 2011-08-23 15:26 ` Akinobu Mita
-1 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-23 15:26 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel, linux-mm
2011/8/23 Andrew Morton <akpm@linux-foundation.org>:
> This seems more complicated than is needed. Couldn't we just do
>
> static void poison_page(struct page *page)
> {
> void *addr;
>
> preempt_disable();
> addr = kmap_atomic(page);
> set_page_poison(page);
> memset(addr, PAGE_POISON, PAGE_SIZE);
> kunmap_atomic(addr);
> preempt_enable();
> }
>
> ?
This code looks much better. I'll update the patch.
^ permalink raw reply [flat|nested] 30+ messages in thread
* Re: [PATCH 2/4] debug-pagealloc: add support for highmem pages
@ 2011-08-23 15:26 ` Akinobu Mita
0 siblings, 0 replies; 30+ messages in thread
From: Akinobu Mita @ 2011-08-23 15:26 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel, linux-mm
2011/8/23 Andrew Morton <akpm@linux-foundation.org>:
> This seems more complicated than is needed. Couldn't we just do
>
> static void poison_page(struct page *page)
> {
> void *addr;
>
> preempt_disable();
> addr = kmap_atomic(page);
> set_page_poison(page);
> memset(addr, PAGE_POISON, PAGE_SIZE);
> kunmap_atomic(addr);
> preempt_enable();
> }
>
> ?
This code looks much better. I'll update the patch.
--
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^ permalink raw reply [flat|nested] 30+ messages in thread
end of thread, other threads:[~2011-08-23 15:26 UTC | newest]
Thread overview: 30+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-08-22 16:29 [PATCH 0/4] debug-pagealloc improvements Akinobu Mita
2011-08-22 16:29 ` Akinobu Mita
2011-08-22 16:29 ` [PATCH 1/4] debug-pagealloc: use plain __ratelimit() instead of printk_ratelimit() Akinobu Mita
2011-08-22 16:29 ` Akinobu Mita
2011-08-22 16:29 ` [PATCH 2/4] debug-pagealloc: add support for highmem pages Akinobu Mita
2011-08-22 16:29 ` Akinobu Mita
2011-08-22 20:43 ` Andrew Morton
2011-08-22 20:43 ` Andrew Morton
2011-08-23 15:26 ` Akinobu Mita
2011-08-23 15:26 ` Akinobu Mita
2011-08-22 16:29 ` [PATCH 3/4] string: introduce memchr_inv Akinobu Mita
2011-08-22 16:29 ` Akinobu Mita
2011-08-22 16:57 ` Pekka Enberg
2011-08-22 16:57 ` Pekka Enberg
2011-08-22 17:09 ` Jörn Engel
2011-08-22 17:09 ` Jörn Engel
2011-08-22 20:52 ` Andrew Morton
2011-08-22 20:52 ` Andrew Morton
2011-08-22 21:50 ` Andrew Morton
2011-08-22 21:50 ` Andrew Morton
2011-08-22 21:50 ` Andrew Morton
2011-08-22 21:56 ` Eric Dumazet
2011-08-22 21:56 ` Eric Dumazet
2011-08-22 21:56 ` Eric Dumazet
2011-08-22 20:59 ` Geert Uytterhoeven
2011-08-22 20:59 ` Geert Uytterhoeven
2011-08-23 14:31 ` Christoph Lameter
2011-08-23 14:31 ` Christoph Lameter
2011-08-22 16:29 ` [PATCH 4/4] debug-pagealloc: use memchr_inv Akinobu Mita
2011-08-22 16:29 ` Akinobu Mita
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