> I don't think I've ever really seen code to diagnose this.
>
> A simplistic approach would be to add eight or so ulongs into struct page,
> populate them with builtin_return_address(0...7) at allocation time, then
> modify sysrq-m to walk mem_map[] printing it all out for pages which have
> page_count() > 0. That'd find the culprit.
Hi Andrew
I put something similar together of what you described but I made it a
proc-file. It lists all pages owned by some caller and keeps a backtrace
of max 8 addresses. Each page has an order, -1 for unused and if used it lists
the order under which the first page is allocated, the rest in the group are
kept -1.
Below is also a program to sort the enormous amount of
output, it will group together backtraces that are alike and list them like:
5 times: Page allocated via order 0
[0xffffffff8015861f] __get_free_pages+31
[0xffffffff8015c0ef] cache_alloc_refill+719
[0xffffffff8015bd74] kmem_cache_alloc+84
[0xffffffff8015bddc] alloc_arraycache+60
[0xffffffff8015d15d] do_tune_cpucache+93
[0xffffffff8015bbf8] cache_alloc_debugcheck_after+280
[0xffffffff8015d31d] enable_cpucache+93
[0xffffffff8015d8a5] kmem_cache_create+1365
It's a bit of hackety-hack in the function trace routines because doing
__builtin_return_address(0) - 7 doesn't work very well when it
runs out of the stack and the function itself doesn't check for it.
Tested on x86 with and without CONFIG_FRAME_POINTER and x86-64 (which
might are the only archs it'll work on). I hope you like it ;)
Suggested use is
cat /proc/page_owner > pgown;
./below_program pgown pgsorted;
vim pgsorted
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
struct block_list {
struct block_list *next;
char *txt;
int len;
int num;
};
struct block_list *block_head;
int read_block(char *buf, int fd)
{
int ret = 0, rd = 0;
int hit = 0;
char *curr = buf;
for (;;) {
rd = read(fd, curr, 1);
if (rd <= 0)
return -1;
ret += rd;
if (*curr == '\n' && hit == 1)
return ret - 1;
else if (*curr == '\n')
hit = 1;
else
hit = 0;
curr++;
}
}
int find_duplicate(char *buf, int len)
{
struct block_list *iterate, *item, *prev;
char *txt;
iterate = block_head;
while (iterate) {
if (len != iterate->len)
goto iterate;
if (!memcmp(buf, iterate->txt, len)) {
iterate->num++;
return 1;
}
iterate:
iterate = iterate->next;
}
/* this block didn't exist */
txt = malloc(len);
item = malloc(sizeof(struct block_list));
strncpy(txt, buf, len);
item->len = len;
item->txt = txt;
item->num = 1;
item->next = NULL;
if (block_head) {
prev = block_head->next;
block_head->next = item;
item->next = prev;
} else
block_head = item;
return 0;
}
int main(int argc, char **argv)
{
int fdin, fdout;
char buf[1024];
int ret;
struct block_list *item;
fdin = open(argv[1], O_RDONLY);
fdout = open(argv[2], O_CREAT | O_RDWR | O_EXCL, S_IWUSR | S_IRUSR);
if (fdin < 0 || fdout < 0) {
printf("Usage: ./program <input> <output>\n");
perror("open: ");
exit(2);
}
for(;;) {
ret = read_block(buf, fdin);
if (ret < 0)
break;
buf[ret] = '\0';
find_duplicate(buf, ret);
}
for (item = block_head; item; item = item->next) {
int written;
/* errors? what errors... */
ret = snprintf(buf, 1024, "%d times: ", item->num);
written = write(fdout, buf, ret);
written = write(fdout, item->txt, item->len);
written = write(fdout, "\n", 1);
}
return 0;
}
===== fs/proc/proc_misc.c 1.113 vs edited =====
--- 1.113/fs/proc/proc_misc.c 2005-01-12 01:42:35 +01:00
+++ edited/fs/proc/proc_misc.c 2005-01-24 00:59:23 +01:00
@@ -534,6 +534,62 @@ static struct file_operations proc_sysrq
};
#endif
+#if 1
+#include <linux/bootmem.h>
+#include <linux/kallsyms.h>
+static ssize_t
+read_page_owner(struct file *file, char __user *buf, size_t count, loff_t
*ppos)
+{
+ struct page *start = pfn_to_page(min_low_pfn);
+ static struct page *page;
+ char *kbuf, *modname;
+ const char *symname;
+ int ret = 0, next_idx = 1;
+ char namebuf[128];
+ unsigned long offset = 0, symsize;
+ int i;
+
+ page = start + *ppos;
+ for (; page < pfn_to_page(max_pfn); page++) {
+ if (page->order >= 0)
+ break;
+ next_idx++;
+ continue;
+ }
+
+ if (page >= pfn_to_page(max_pfn))
+ return 0;
+
+ *ppos += next_idx;
+
+ kbuf = kmalloc(count, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+
+ ret = snprintf(kbuf, count, "Page allocated via order %d\n",
page->order);
+
+ for (i = 0; i < 8; i++) {
+ if (!page->trace[i])
+ break;
+ symname = kallsyms_lookup(page->trace[i], &symsize, &offset,
&modname, namebuf);
+ ret += snprintf(kbuf + ret, count - ret, "[0x%lx] %s+%lu\n",
+ page->trace[i], namebuf, offset);
+ }
+
+ ret += snprintf(kbuf + ret, count -ret, "\n");
+
+ if (copy_to_user(buf, kbuf, ret))
+ ret = -EFAULT;
+
+ kfree(kbuf);
+ return ret;
+}
+
+static struct file_operations proc_page_owner_operations = {
+ .read = read_page_owner,
+};
+#endif
+
struct proc_dir_entry *proc_root_kcore;
void create_seq_entry(char *name, mode_t mode, struct file_operations *f)
@@ -610,6 +666,13 @@ void __init proc_misc_init(void)
entry = create_proc_entry("ppc_htab", S_IRUGO|S_IWUSR, NULL);
if (entry)
entry->proc_fops = &ppc_htab_operations;
+ }
+#endif
+#if 1
+ entry = create_proc_entry("page_owner", S_IWUSR | S_IRUGO, NULL);
+ if (entry) {
+ entry->proc_fops = &proc_page_owner_operations;
+ entry->size = 1024;
}
#endif
}
===== include/linux/mm.h 1.211 vs edited =====
--- 1.211/include/linux/mm.h 2005-01-11 02:29:23 +01:00
+++ edited/include/linux/mm.h 2005-01-23 23:22:52 +01:00
@@ -260,6 +260,10 @@ struct page {
void *virtual; /* Kernel virtual address (NULL if
not kmapped, ie. highmem) */
#endif /* WANT_PAGE_VIRTUAL */
+#if 1
+ int order;
+ unsigned long trace[8];
+#endif
};
/*
===== mm/page_alloc.c 1.254 vs edited =====
--- 1.254/mm/page_alloc.c 2005-01-11 02:29:33 +01:00
+++ edited/mm/page_alloc.c 2005-01-24 01:04:38 +01:00
@@ -103,6 +103,7 @@ static void bad_page(const char *functio
tainted |= TAINT_BAD_PAGE;
}
+
#ifndef CONFIG_HUGETLB_PAGE
#define prep_compound_page(page, order) do { } while (0)
#define destroy_compound_page(page, order) do { } while (0)
@@ -680,6 +681,41 @@ int zone_watermark_ok(struct zone *z, in
return 1;
}
+static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
+{
+ return p > (void *)tinfo &&
+ p < (void *)tinfo + THREAD_SIZE - 3;
+}
+
+static inline void __stack_trace(struct page *page, unsigned long *stack,
unsigned long bp)
+{
+ int i = 0;
+ unsigned long addr;
+ struct thread_info *tinfo = (struct thread_info *)
+ ((unsigned long)stack & (~(THREAD_SIZE - 1)));
+
+ memset(page->trace, 0, sizeof(long) * 8);
+
+#ifdef CONFIG_FRAME_POINTER
+ while (valid_stack_ptr(tinfo, (void *)bp)) {
+ addr = *(unsigned long *)(bp + sizeof(long));
+ page->trace[i] = addr;
+ if (++i >= 8)
+ break;
+ bp = *(unsigned long *)bp;
+ }
+#else
+ while (valid_stack_ptr(tinfo, stack)) {
+ addr = *stack++;
+ if (__kernel_text_address(addr)) {
+ page->trace[i] = addr;
+ if (++i >= 8)
+ break;
+ }
+ }
+#endif
+}
+
/*
* This is the 'heart' of the zoned buddy allocator.
*
@@ -709,6 +745,7 @@ __alloc_pages(unsigned int gfp_mask, uns
int alloc_type;
int do_retry;
int can_try_harder;
+ unsigned long address, bp;
might_sleep_if(wait);
@@ -825,6 +862,14 @@ nopage:
return NULL;
got_pg:
zone_statistics(zonelist, z);
+ page->order = (int) order;
+#ifdef X86_64
+ asm ("movq %%rbp, %0" : "=r" (bp) : );
+#else
+ asm ("movl %%ebp, %0" : "=r" (bp) : );
+#endif
+ __stack_trace(page, &address, bp);
+
return page;
}
@@ -877,6 +922,7 @@ fastcall void __free_pages(struct page *
free_hot_page(page);
else
__free_pages_ok(page, order);
+ page->order = -1;
}
}
@@ -1508,6 +1554,7 @@ void __init memmap_init_zone(unsigned lo
set_page_address(page, __va(start_pfn << PAGE_SHIFT));
#endif
start_pfn++;
+ page->order = -1;
}
}
-
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