Revision 140d0b2108faebc77c6523296e211e509cb9f5f9 authored by Linus Torvalds on 05 August 2011, 05:35:59 UTC, committed by Linus Torvalds on 05 August 2011, 05:35:59 UTC
This isn't really critical any more, since other patches (commit 298507d4d2cf: "shm: optimize exit_shm()") have caused us to not actually need to touch the rw_mutex unless there are actual shm segments associated with the namespace, but we really should do tne shm_init_ns() earlier than we do now. This, together with commit 288d5abec831 ("Boot up with usermodehelper disabled") will mean that we really do initialize the initial ipc namespace data structure before we run any tasks. Tested-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 24f0eed
debug-pagealloc.c
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/page-debug-flags.h>
#include <linux/poison.h>
static inline void set_page_poison(struct page *page)
{
__set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
}
static inline void clear_page_poison(struct page *page)
{
__clear_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
}
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;
}
set_page_poison(page);
addr = page_address(page);
memset(addr, PAGE_POISON, PAGE_SIZE);
}
static void poison_pages(struct page *page, int n)
{
int i;
for (i = 0; i < n; i++)
poison_page(page + i);
}
static bool single_bit_flip(unsigned char a, unsigned char b)
{
unsigned char error = a ^ b;
return error && !(error & (error - 1));
}
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)
return;
for (end = mem + bytes - 1; end > start; end--) {
if (*end != PAGE_POISON)
break;
}
if (!printk_ratelimit())
return;
else if (start == end && single_bit_flip(*start, PAGE_POISON))
printk(KERN_ERR "pagealloc: single bit error\n");
else
printk(KERN_ERR "pagealloc: memory corruption\n");
print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start,
end - start + 1, 1);
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);
return;
}
if (page_poison(page)) {
void *addr = page_address(page);
check_poison_mem(addr, PAGE_SIZE);
clear_page_poison(page);
}
}
static void unpoison_pages(struct page *page, int n)
{
int i;
for (i = 0; i < n; i++)
unpoison_page(page + i);
}
void kernel_map_pages(struct page *page, int numpages, int enable)
{
if (!debug_pagealloc_enabled)
return;
if (enable)
unpoison_pages(page, numpages);
else
poison_pages(page, numpages);
}
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