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SubjectRe: /proc/slab garbage
On Sat, Jun 01, 2002 at 02:47:37PM -0400, Tom Vier wrote:
> when i cat /proc/slabinfo, after the normal info, it's spits out garbage;
> seemingly random memory contents. it's printing past the end of the buffer.
> i can email an example upon request.
>
> Linux zero 2.4.19-pre9 #1 Tue May 28 20:54:41 EDT 2002 alpha unknown

The patch below should fix it properly: it's a backport of Al Viro's
seqfile patch for slabinfo. The first part also reverts the vnsprintf
changes made previously as seq file relies on C99 style behaviour
of snprintf. It's against a 2.4.19ish tree, but I've not checked
that it applies against 2.4.19-pre9.

-ben
--
"You will be reincarnated as a toad; and you will be much happier."

diff -urN linux/lib/vsprintf.c linux.diff/lib/vsprintf.c
--- linux/lib/vsprintf.c Mon May 27 17:51:27 2002
+++ linux.diff/lib/vsprintf.c Mon May 27 17:54:21 2002
@@ -172,41 +172,50 @@
if (!(type&(ZEROPAD+LEFT))) {
while(size-->0) {
if (buf <= end)
- *buf++ = ' ';
+ *buf = ' ';
+ ++buf;
}
}
if (sign) {
if (buf <= end)
- *buf++ = sign;
+ *buf = sign;
+ ++buf;
}
if (type & SPECIAL) {
if (base==8) {
if (buf <= end)
- *buf++ = '0';
+ *buf = '0';
+ ++buf;
} else if (base==16) {
if (buf <= end)
- *buf++ = '0';
+ *buf = '0';
+ ++buf;
if (buf <= end)
- *buf++ = digits[33];
+ *buf = digits[33];
+ ++buf;
}
}
if (!(type & LEFT)) {
while (size-- > 0) {
if (buf <= end)
- *buf++ = c;
+ *buf = c;
+ ++buf;
}
}
while (i < precision--) {
if (buf <= end)
- *buf++ = '0';
+ *buf = '0';
+ ++buf;
}
while (i-- > 0) {
if (buf <= end)
- *buf++ = tmp[i];
+ *buf = tmp[i];
+ ++buf;
}
while (size-- > 0) {
if (buf <= end)
- *buf++ = ' ';
+ *buf = ' ';
+ ++buf;
}
return buf;
}
@@ -238,10 +247,6 @@
/* 'z' support added 23/7/1999 S.H. */
/* 'z' changed to 'Z' --davidm 1/25/99 */

- /* Enforce absolute minimum size: one character + the trailing 0 */
- if (size < 2)
- return 0;
-
str = buf;
end = buf + size - 1;

@@ -253,7 +258,8 @@
for (; *fmt ; ++fmt) {
if (*fmt != '%') {
if (str <= end)
- *str++ = *fmt;
+ *str = *fmt;
+ ++str;
continue;
}

@@ -317,15 +323,18 @@
if (!(flags & LEFT)) {
while (--field_width > 0) {
if (str <= end)
- *str++ = ' ';
+ *str = ' ';
+ ++str;
}
}
c = (unsigned char) va_arg(args, int);
if (str <= end)
- *str++ = c;
+ *str = c;
+ ++str;
while (--field_width > 0) {
if (str <= end)
- *str++ = ' ';
+ *str = ' ';
+ ++str;
}
continue;

@@ -339,16 +348,19 @@
if (!(flags & LEFT)) {
while (len < field_width--) {
if (str <= end)
- *str++ = ' ';
+ *str = ' ';
+ ++str;
}
}
for (i = 0; i < len; ++i) {
if (str <= end)
- *str++ = *s++;
+ *str = *s;
+ ++str; ++s;
}
while (len < field_width--) {
if (str <= end)
- *str++ = ' ';
+ *str = ' ';
+ ++str;
}
continue;

@@ -380,7 +392,8 @@

case '%':
if (str <= end)
- *str++ = '%';
+ *str = '%';
+ ++str;
continue;

/* integer number formats - set up the flags and "break" */
@@ -402,10 +415,12 @@

default:
if (str <= end)
- *str++ = '%';
+ *str = '%';
+ ++str;
if (*fmt) {
if (str <= end)
- *str++ = *fmt;
+ *str = *fmt;
+ ++str;
} else {
--fmt;
}
diff -urN linux.orig/fs/proc/proc_misc.c linux.work/fs/proc/proc_misc.c
--- linux.orig/fs/proc/proc_misc.c Mon May 27 17:14:07 2002
+++ linux.work/fs/proc/proc_misc.c Mon May 27 17:14:39 2002
@@ -289,6 +289,20 @@
};
#endif

+extern struct seq_operations slabinfo_op;
+extern ssize_t slabinfo_write(struct file *, const char *, size_t, loff_t *);
+static int slabinfo_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &slabinfo_op);
+}
+static struct file_operations proc_slabinfo_operations = {
+ open: slabinfo_open,
+ read: seq_read,
+ write: slabinfo_write,
+ llseek: seq_lseek,
+ release: seq_release,
+};
+
static int kstat_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
@@ -589,6 +603,7 @@
if (entry)
entry->proc_fops = &proc_kmsg_operations;
create_seq_entry("cpuinfo", 0, &proc_cpuinfo_operations);
+ create_seq_entry("slabinfo",S_IWUSR|S_IRUGO,&proc_slabinfo_operations);
#ifdef CONFIG_MODULES
create_seq_entry("ksyms", 0, &proc_ksyms_operations);
#endif
@@ -613,8 +628,4 @@
entry->proc_fops = &ppc_htab_operations;
}
#endif
- entry = create_proc_read_entry("slabinfo", S_IWUSR | S_IRUGO, NULL,
- slabinfo_read_proc, NULL);
- if (entry)
- entry->write_proc = slabinfo_write_proc;
}
diff -urN linux.orig/include/linux/slab.h linux.work/include/linux/slab.h
--- linux.orig/include/linux/slab.h Mon May 27 17:14:07 2002
+++ linux.work/include/linux/slab.h Mon May 27 17:14:39 2002
@@ -62,10 +62,6 @@
extern void kfree(const void *);

extern int FASTCALL(kmem_cache_reap(int));
-extern int slabinfo_read_proc(char *page, char **start, off_t off,
- int count, int *eof, void *data);
-extern int slabinfo_write_proc(struct file *file, const char *buffer,
- unsigned long count, void *data);

/* System wide caches */
extern kmem_cache_t *vm_area_cachep;
diff -urN linux.orig/mm/slab.c linux.work/mm/slab.c
--- linux.orig/mm/slab.c Mon May 27 17:14:07 2002
+++ linux.work/mm/slab.c Mon May 27 17:14:39 2002
@@ -72,6 +72,8 @@
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/init.h>
+#include <linux/compiler.h>
+#include <linux/seq_file.h>
#include <asm/uaccess.h>

/*
@@ -1849,31 +1851,56 @@
}

#ifdef CONFIG_PROC_FS
-/* /proc/slabinfo
- * cache-name num-active-objs total-objs
- * obj-size num-active-slabs total-slabs
- * num-pages-per-slab
- */
-#define FIXUP(t) \
- do { \
- if (len <= off) { \
- off -= len; \
- len = 0; \
- } else { \
- if (len-off >= count) \
- goto t; \
- } \
- } while (0)

-static int proc_getdata (char*page, char**start, off_t off, int count)
+static void *s_start(struct seq_file *m, loff_t *pos)
{
+ loff_t n = *pos;
struct list_head *p;
- int len = 0;

- /* Output format version, so at least we can change it without _too_
- * many complaints.
- */
- len += snprintf(page+len, PAGE_SIZE-len, "slabinfo - version: 1.1"
+ down(&cache_chain_sem);
+ if (!n)
+ return (void *)1;
+ p = &cache_cache.next;
+ while (--n) {
+ p = p->next;
+ if (p == &cache_cache.next)
+ return NULL;
+ }
+ return list_entry(p, kmem_cache_t, next);
+}
+
+static void *s_next(struct seq_file *m, void *p, loff_t *pos)
+{
+ kmem_cache_t *cachep = p;
+ ++*pos;
+ if (p == (void *)1)
+ return &cache_cache;
+ cachep = list_entry(cachep->next.next, kmem_cache_t, next);
+ return cachep == &cache_cache ? NULL : cachep;
+}
+
+static void s_stop(struct seq_file *m, void *p)
+{
+ up(&cache_chain_sem);
+}
+
+static int s_show(struct seq_file *m, void *p)
+{
+ kmem_cache_t *cachep = p;
+ struct list_head *q;
+ slab_t *slabp;
+ unsigned long active_objs;
+ unsigned long num_objs;
+ unsigned long active_slabs = 0;
+ unsigned long num_slabs;
+ const char *name;
+
+ if (p == (void*)1) {
+ /*
+ * Output format version, so at least we can change it
+ * without _too_ many complaints.
+ */
+ seq_puts(m, "slabinfo - version: 1.1"
#if STATS
" (statistics)"
#endif
@@ -1881,117 +1908,91 @@
" (SMP)"
#endif
"\n");
- FIXUP(got_data);
-
- down(&cache_chain_sem);
- p = &cache_cache.next;
- do {
- kmem_cache_t *cachep;
- struct list_head *q;
- slab_t *slabp;
- unsigned long active_objs;
- unsigned long num_objs;
- unsigned long active_slabs = 0;
- unsigned long num_slabs;
- cachep = list_entry(p, kmem_cache_t, next);
+ return 0;
+ }

- spin_lock_irq(&cachep->spinlock);
- active_objs = 0;
- num_slabs = 0;
- list_for_each(q,&cachep->slabs_full) {
- slabp = list_entry(q, slab_t, list);
- if (slabp->inuse != cachep->num)
- BUG();
- active_objs += cachep->num;
- active_slabs++;
- }
- list_for_each(q,&cachep->slabs_partial) {
- slabp = list_entry(q, slab_t, list);
- if (slabp->inuse == cachep->num || !slabp->inuse)
- BUG();
- active_objs += slabp->inuse;
- active_slabs++;
- }
- list_for_each(q,&cachep->slabs_free) {
- slabp = list_entry(q, slab_t, list);
- if (slabp->inuse)
- BUG();
- num_slabs++;
- }
- num_slabs+=active_slabs;
- num_objs = num_slabs*cachep->num;
+ spin_lock_irq(&cachep->spinlock);
+ active_objs = 0;
+ num_slabs = 0;
+ list_for_each(q,&cachep->slabs_full) {
+ slabp = list_entry(q, slab_t, list);
+ if (slabp->inuse != cachep->num)
+ BUG();
+ active_objs += cachep->num;
+ active_slabs++;
+ }
+ list_for_each(q,&cachep->slabs_partial) {
+ slabp = list_entry(q, slab_t, list);
+ if (slabp->inuse == cachep->num || !slabp->inuse)
+ BUG();
+ active_objs += slabp->inuse;
+ active_slabs++;
+ }
+ list_for_each(q,&cachep->slabs_free) {
+ slabp = list_entry(q, slab_t, list);
+ if (slabp->inuse)
+ BUG();
+ num_slabs++;
+ }
+ num_slabs+=active_slabs;
+ num_objs = num_slabs*cachep->num;

- len += snprintf(page+len, PAGE_SIZE-len,
- "%-17s %6lu %6lu %6u %4lu %4lu %4u",
- cachep->name, active_objs, num_objs, cachep->objsize,
- active_slabs, num_slabs, (1<<cachep->gfporder));
+ name = cachep->name;
+ {
+ char tmp;
+ if (__get_user(tmp, name))
+ name = "broken";
+ }
+
+ seq_printf(m, "%-17s %6lu %6lu %6u %4lu %4lu %4u",
+ name, active_objs, num_objs, cachep->objsize,
+ active_slabs, num_slabs, (1<<cachep->gfporder));

#if STATS
- {
- unsigned long errors = cachep->errors;
- unsigned long high = cachep->high_mark;
- unsigned long grown = cachep->grown;
- unsigned long reaped = cachep->reaped;
- unsigned long allocs = cachep->num_allocations;
-
- len += snprintf(page+len, PAGE_SIZE-len,
- " : %6lu %7lu %5lu %4lu %4lu",
- high, allocs, grown, reaped, errors);
- }
+ {
+ unsigned long errors = cachep->errors;
+ unsigned long high = cachep->high_mark;
+ unsigned long grown = cachep->grown;
+ unsigned long reaped = cachep->reaped;
+ unsigned long allocs = cachep->num_allocations;
+
+ seq_printf(m, " : %6lu %7lu %5lu %4lu %4lu",
+ high, allocs, grown, reaped, errors);
+ }
#endif
#ifdef CONFIG_SMP
- {
- cpucache_t *cc = cc_data(cachep);
- unsigned int batchcount = cachep->batchcount;
- unsigned int limit;
-
- if (cc)
- limit = cc->limit;
- else
- limit = 0;
- len += snprintf(page+len, PAGE_SIZE-len, " : %4u %4u",
- limit, batchcount);
- }
+ {
+ cpucache_t *cc = cc_data(cachep);
+ unsigned int batchcount = cachep->batchcount;
+ unsigned int limit;
+
+ if (cc)
+ limit = cc->limit;
+ else
+ limit = 0;
+ seq_printf(m, " : %4u %4u",
+ limit, batchcount);
+ }
#endif
#if STATS && defined(CONFIG_SMP)
- {
- unsigned long allochit = atomic_read(&cachep->allochit);
- unsigned long allocmiss = atomic_read(&cachep->allocmiss);
- unsigned long freehit = atomic_read(&cachep->freehit);
- unsigned long freemiss = atomic_read(&cachep->freemiss);
- len += snprintf(page+len, PAGE_SIZE-len,
- " : %6lu %6lu %6lu %6lu",
- allochit, allocmiss, freehit, freemiss);
- }
-#endif
- len += snprintf(page+len, PAGE_SIZE-len, "\n");
- spin_unlock_irq(&cachep->spinlock);
- FIXUP(got_data_up);
- p = cachep->next.next;
- if (len > PAGE_SIZE - 512)
- break;
- } while (p != &cache_cache.next);
-got_data_up:
- up(&cache_chain_sem);
-
-got_data:
- if (off < len) {
- *start = page+off;
- return len;
+ {
+ unsigned long allochit = atomic_read(&cachep->allochit);
+ unsigned long allocmiss = atomic_read(&cachep->allocmiss);
+ unsigned long freehit = atomic_read(&cachep->freehit);
+ unsigned long freemiss = atomic_read(&cachep->freemiss);
+ seq_printf(m, " : %6lu %6lu %6lu %6lu",
+ allochit, allocmiss, freehit, freemiss);
}
+#endif
+ spin_unlock_irq(&cachep->spinlock);
+ seq_putc(m, '\n');
return 0;
}

/**
- * slabinfo_read_proc - generates /proc/slabinfo
- * @page: scratch area, one page long
- * @start: pointer to the pointer to the output buffer
- * @off: offset within /proc/slabinfo the caller is interested in
- * @count: requested len in bytes
- * @eof: eof marker
- * @data: unused
+ * slabinfo_op - iterator that generates /proc/slabinfo
*
- * The contents of the buffer are
+ * Output layout:
* cache-name
* num-active-objs
* total-objs
@@ -2001,28 +2002,24 @@
* num-pages-per-slab
* + further values on SMP and with statistics enabled
*/
-int slabinfo_read_proc (char *page, char **start, off_t off,
- int count, int *eof, void *data)
-{
- int len = proc_getdata(page, start, off, count);
- len -= (*start-page);
- if (len <= count)
- *eof = 1;
- if (len>count) len = count;
- if (len<0) len = 0;
- return len;
-}
+
+struct seq_operations slabinfo_op = {
+ start: s_start,
+ next: s_next,
+ stop: s_stop,
+ show: s_show
+};

#define MAX_SLABINFO_WRITE 128
/**
- * slabinfo_write_proc - SMP tuning for the slab allocator
+ * slabinfo_write - SMP tuning for the slab allocator
* @file: unused
* @buffer: user buffer
* @count: data len
* @data: unused
*/
-int slabinfo_write_proc (struct file *file, const char *buffer,
- unsigned long count, void *data)
+ssize_t slabinfo_write(struct file *file, const char *buffer,
+ size_t count, loff_t *ppos)
{
#ifdef CONFIG_SMP
char kbuf[MAX_SLABINFO_WRITE+1], *tmp;
-
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