Index: mm//filemap.c
===================================================================
RCS file: /var/cvs/linux/mm/filemap.c,v
retrieving revision 1.1.1.1.2.14
diff -u -r1.1.1.1.2.14 filemap.c
--- filemap.c 1998/12/17 16:34:07 1.1.1.1.2.14
+++ linux/mm/filemap.c 1998/12/19 15:37:30
@@ -1210,8 +1210,9 @@
unsigned long address, unsigned int flags)
{
pte_t pte = *ptep;
- unsigned long page;
+ unsigned long page = pte_page(pte);
int error;
+ struct page * map = mem_map + MAP_NR(page);
if (!(flags & MS_INVALIDATE)) {
if (!pte_present(pte))
@@ -1220,10 +1221,9 @@
return 0;
flush_page_to_ram(pte_page(pte));
flush_cache_page(vma, address);
- set_pte(ptep, pte_mkclean(pte));
+ set_pte(ptep, pte_wrprotect(pte_mkclean(pte)));
flush_tlb_page(vma, address);
- page = pte_page(pte);
- atomic_inc(&mem_map[MAP_NR(page)].count);
+ atomic_inc(&map->count);
} else {
if (pte_none(pte))
return 0;
@@ -1234,14 +1234,15 @@
swap_free(pte_val(pte));
return 0;
}
- page = pte_page(pte);
if (!pte_dirty(pte) || flags == MS_INVALIDATE) {
- free_page(page);
+ __free_page(map);
return 0;
}
}
- error = filemap_write_page(vma, address - vma->vm_start + vma->vm_offset, page);
- free_page(page);
+ if (!PageTestAndSetClean(map))
+ error = filemap_write_page(vma, address - vma->vm_start +
+ vma->vm_offset, page);
+ __free_page(map);
return error;
}
Index: mm//memory.c
===================================================================
RCS file: /var/cvs/linux/mm/memory.c,v
retrieving revision 1.1.1.1.2.1
diff -u -r1.1.1.1.2.1 memory.c
--- memory.c 1998/11/27 10:41:41 1.1.1.1.2.1
+++ linux/mm/memory.c 1998/12/19 15:32:48
@@ -623,11 +623,10 @@
unsigned long address, pte_t *page_table)
{
pte_t pte;
- unsigned long old_page, new_page;
+ unsigned long old_page;
struct page * page_map;
pte = *page_table;
- new_page = __get_free_page(GFP_USER);
/* Did someone else copy this page for us while we slept? */
if (pte_val(*page_table) != pte_val(pte))
goto end_wp_page;
@@ -640,16 +639,25 @@
goto bad_wp_page;
tsk->min_flt++;
page_map = mem_map + MAP_NR(old_page);
-
+
+ /* If the page is clean we just know why it was write protect -arca */
+ if (PageTestAndClearClean(page_map))
+ {
+ set_pte(page_table, pte_mkdirty(pte_mkwrite(pte)));
+ goto end_wp_page;
+ }
+
/*
* Do we need to copy?
*/
if (is_page_shared(page_map)) {
+ unsigned long new_page;
unlock_kernel();
+ new_page = __get_free_page(GFP_USER);
if (!new_page)
return 0;
- if (PageReserved(mem_map + MAP_NR(old_page)))
+ if (PageReserved(page_map))
++vma->vm_mm->rss;
copy_cow_page(old_page,new_page);
flush_page_to_ram(old_page);
@@ -670,16 +678,15 @@
flush_cache_page(vma, address);
set_pte(page_table, pte_mkdirty(pte_mkwrite(pte)));
flush_tlb_page(vma, address);
+ return 1;
end_wp_page:
- if (new_page)
- free_page(new_page);
+ unlock_kernel();
return 1;
bad_wp_page:
+ unlock_kernel();
printk("do_wp_page: bogus page at address %08lx (%08lx)\n",address,old_page);
send_sig(SIGKILL, tsk, 1);
- if (new_page)
- free_page(new_page);
return 0;
}
Index: mm//page_alloc.c
===================================================================
RCS file: /var/cvs/linux/mm/page_alloc.c,v
retrieving revision 1.1.1.1.2.6
diff -u -r1.1.1.1.2.6 page_alloc.c
--- page_alloc.c 1998/12/17 14:44:43 1.1.1.1.2.6
+++ linux/mm/page_alloc.c 1998/12/19 15:52:43
@@ -151,6 +151,7 @@
if (!PageReserved(page) && atomic_dec_and_test(&page->count)) {
if (PageSwapCache(page))
panic ("Freeing swap cache page");
+ PageClearClean(page);
free_pages_ok(page->map_nr, 0);
return;
}
@@ -172,6 +173,7 @@
if (atomic_dec_and_test(&map->count)) {
if (PageSwapCache(map))
panic ("Freeing swap cache pages");
+ PageClearClean(map);
free_pages_ok(map_nr, order);
return;
}
Index: include/linux//mm.h
===================================================================
RCS file: /var/cvs/linux/include/linux/mm.h,v
retrieving revision 1.1.1.1.2.5
diff -u -r1.1.1.1.2.5 mm.h
--- mm.h 1998/12/17 14:44:37 1.1.1.1.2.5
+++ linux/include/linux/mm.h 1998/12/19 15:29:31
@@ -136,6 +136,7 @@
#define PG_Slab 8
#define PG_swap_cache 9
#define PG_skip 10
+#define PG_clean 11
#define PG_reserved 31
/* Make it prettier to test the above... */
@@ -149,16 +150,24 @@
#define PageDMA(page) (test_bit(PG_DMA, &(page)->flags))
#define PageSlab(page) (test_bit(PG_Slab, &(page)->flags))
#define PageSwapCache(page) (test_bit(PG_swap_cache, &(page)->flags))
+#define PageClean(page) (test_bit(PG_clean, &(page)->flags))
#define PageReserved(page) (test_bit(PG_reserved, &(page)->flags))
#define PageSetSlab(page) (set_bit(PG_Slab, &(page)->flags))
+#define PageSetClean(page) (set_bit(PG_clean, &(page)->flags))
#define PageSetSwapCache(page) (set_bit(PG_swap_cache, &(page)->flags))
+
+#define PageTestAndSetClean(page) \
+ (test_and_set_bit(PG_clean, &(page)->flags))
#define PageTestandSetSwapCache(page) \
(test_and_set_bit(PG_swap_cache, &(page)->flags))
#define PageClearSlab(page) (clear_bit(PG_Slab, &(page)->flags))
+#define PageClearClean(page) (clear_bit(PG_clean, &(page)->flags))
#define PageClearSwapCache(page)(clear_bit(PG_swap_cache, &(page)->flags))
+#define PageTestAndClearClean(page) \
+ (test_and_clear_bit(PG_clean, &(page)->flags))
#define PageTestandClearSwapCache(page) \
(test_and_clear_bit(PG_swap_cache, &(page)->flags))
Seems to work here but I' ve not tested it very well yet. At first I
forgot to clean the PG_clean flag in *free_pages and you can guess that I
had to reboot very soon after the first msync ;). It was not msyncing
anymore!! Luckily I understood the culprit after a msec.
NOTE, the do_wp_page() patch I think it' s needed also in the stock
kernel, there are some unbalanced unlock_kernel() otherwise and we would
run a __get_free_pages() even if not needed and while the kernel lock was
locked (maybe it was intentional? do we need the big kernel lock while we
run __get_free_pages() in do_wp_page?). You only need to reverse:
-
+
+ /* If the page is clean we just know why it was write protect -arca */
+ if (PageTestAndClearClean(page_map))
+ {
+ set_pte(page_table, pte_mkdirty(pte_mkwrite(pte)));
+ goto end_wp_page;
+ }
+
Andrea Arcangeli
-
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