seg_t mm_dup(seg_t base)
{
register struct malloc_hole *o, *m;
size_t i;
debug("MALLOC: mm_dup()\n");
o = find_hole(&memmap, base);
if (o->flags != HOLE_USED)
panic("bad/swapped hole");
#ifdef CONFIG_SWAP
while ((m = best_fit_hole(&memmap, o->extent)) == NULL) {
seg_t s = swap_strategy(NULL);
if (!s || swap_out(s) == -1)
return NULL;
}
#else
m = best_fit_hole(&memmap, o->extent);
if (m == NULL)
return NULL;
#endif
split_hole(&memmap, m, o->extent);
m->flags = HOLE_USED;
m->refcount = 1;
i = (o->extent << 4);
fmemcpy(m->page_base, 0, o->page_base, 0, (__u16) i);
return m->page_base;
}
seg_t mm_alloc(segext_t pages)
{
/*
* Which hole fits best ?
*/
register struct malloc_hole *m;
#ifdef CONFIG_SWAP
while ((m = best_fit_hole(&memmap, pages)) == NULL) {
seg_t s = swap_strategy(NULL);
if (s == NULL || swap_out(s) == -1)
return NULL;
}
#else
m = best_fit_hole(&memmap, pages);
if (m == NULL)
return NULL;
#endif
/*
* The hole is (probably) too big
*/
split_hole(&memmap, m, pages);
m->flags = HOLE_USED;
m->refcount = 1;
return m->page_base;
}
paddr_t page_alloc()
{
struct coremap *local_coremap = coremap_list ;
lock_acquire(coremap_lock);
while(local_coremap->next != NULL)
{
if((local_coremap->status & 0x2) == 2 )
{
local_coremap->timestamp = localtime ;
localtime++ ;
local_coremap->pages=1;
local_coremap->status = 1 ;
local_coremap->as = NULL ;
bzero((void *)PADDR_TO_KVADDR(local_coremap->pa),PAGE_SIZE);
lock_release(coremap_lock);
return local_coremap->pa ;
}
local_coremap = local_coremap->next ;
}
paddr_t pa = 0 ;
pa = swap_out(1) ;
lock_release(coremap_lock);
return pa ;
}
/*
* Get physical address of first (actually last :-) free page, and mark it
* used. If no free pages left, return 0.
*/
unsigned long get_free_page(void)
{
unsigned long result;
repeat:
__asm__("std ; repne ; scasb\n\t"
"jne 1f\n\t"
"movb $1,1(%%edi)\n\t"
"sall $12,%%ecx\n\t"
"addl %2,%%ecx\n\t"
"movl %%ecx,%%edx\n\t"
"movl $1024,%%ecx\n\t"
"leal 4092(%%edx),%%edi\n\t"
"rep ; stosl\n\t"
"movl %%edx,%%eax\n"
"1:\tcld"
:"=a" (result)
:"0" (0),"i" (LOW_MEM),"c" (PAGING_PAGES),
"D" (mem_map+PAGING_PAGES-1)
:"di","cx","dx");
if (result >= HIGH_MEMORY)
goto repeat;
if ((result && result < LOW_MEM) || (result & 0xfff)) {
printk("weird result: %08x\n",result);
result = 0;
}
if (!result && swap_out())
goto repeat;
return result;
}
void do_pagefault(struct pf_msg *pmsg)
{
int frame;
int page;
verify_vm_access(pmsg->page_idx, pmsg->word_idx);
frame = find_pgt_index();
page = find_vm_index(frame);
lock_memory();
lock_vm();
lock_pagetable();
//printf("Swapping out frame %d\n", frame);
swap_out(page, frame);
usleep(F);
//printf("Swapping in page %d\n", pmsg->page_idx);
swap_in(pmsg->page_idx, frame);
usleep(F);
page_table[page] = -1;
page_table[pmsg->page_idx] = frame;
unlock_memory();
unlock_vm();
unlock_pagetable();
}
void asignar_marco(pagina_t* * pagina, segmento_t** segmento, uint32_t pid){
marco_t* marco=NULL;
marco = buscar_marco_libre();
//Si no hay ningun marco libre, swappeo
//Si hay un marco libre, se lo asigno a la pagina
if((*pagina)->en_disco){
swap_out(pid, (*segmento)->id, pagina);
}else{
if(marco == NULL){
swap_in(pagina, (*segmento)->id, pid);
}else{
(*pagina)->marco=marco->id;
(*pagina)->tiene_marco= true;
marco->id_proceso = pid;
marco->ocupado= true;
loggear_trace("Se asigno el marco %d a la pagina %d del segmento %d del proceso %d.",
marco->id, (*pagina)->id, (*segmento)->id, pid);
if(cantidad_marcos_libre() == 0){
loggear_info("Espacio de memoria principal lleno");
}
}
}
}
int page_fault(page_table_leaf_t *page_entry) {
frame_t victim = 0;
stats.page_faults++;
/*
* If there are no free frames, then we need to swap something out
*/
if( next_free_frame < 0 ) {
/*
* Pick a victim to swap out
*/
page_replacement_alg(&victim);
/*
* Swap out the page
*/
swap_out(victim);
}
/*
* Swap-In the page
*/
swap_in(page_entry);
return 0;
}
/*! Use the clock algorithm to select a frame to evict and execute the
eviction. */
void * frame_evict(enum palloc_flags flag) {
struct list_elem *ce;
struct thread *ct;
struct frame_table_entry *cf;
int i;
if (f_table.lock.holder != thread_current())
lock_acquire(&f_table.lock); /* Get frame table lock */
if (list_empty(&f_table.table)) {
lock_release(&f_table.lock); /* Nothing to evict */
return NULL;
}
f_table.hand = f_table.hand % list_size(&f_table.table);
ce = list_begin(&f_table.table); /* Begin iteration */
for (i = 0; i < f_table.hand; i++) {
/* Find where the "hand" points to: that is where the
iteration starts */
ce = list_next(ce);
}
while (true) {
cf = list_entry(ce, struct frame_table_entry, elem);
ct = cf->owner;
if (!cf->spt->pinned) {
/* If pinned, skip this frame */
if (pagedir_is_accessed(ct->pagedir, cf->spt->upage))
/* If accessed, clear accessed bit */
pagedir_set_accessed(ct->pagedir, cf->spt->upage, false);
else {
/* Swap out the page! */
if (cf->spt->type != SPT_MMAP) {
cf->spt->fr = NULL;
cf->spt->type = SPT_SWAP;
cf->spt->swap_index = swap_out(cf->physical_addr);
}
/* Write the frame back to the map'd file */
else if (cf->spt->type == SPT_MMAP &&
pagedir_is_dirty(ct->pagedir, cf->spt->upage)) {
cf->spt->fr = NULL;
file_write_at(cf->spt->file, cf->physical_addr,
cf->spt->read_bytes, cf->spt->ofs);
}
/* Clear the frame */
list_remove(ce);
pagedir_clear_page(ct->pagedir, cf->spt->upage);
palloc_free_page(cf->physical_addr);
free(cf);
lock_release(&f_table.lock);
return palloc_get_page(flag);
}
}
ce = list_next(ce);
++f_table.hand;
if (ce == list_end(&f_table.table)) { /* Iterate circularly */
ce = list_begin(&f_table.table);
f_table.hand = 0;
}
}
}
/*
* Do an iteration of the swapper
*/
int do_swapper_run(register struct task_struct *swapin_target)
{
while (make_runnable(swapin_target) == -1) {
seg_t t = swap_strategy(swapin_target);
if (!t || swap_out(t) == -1)
return -1;
}
return 0;
}
void page_replacement(void *vaddr)
{
uint32_t *paddr,*lru_page;
if ((paddr = palloc_get_page(PAL_USER)) != NULL)
swap_in(vaddr, paddr);
else
{
lru_page = lru_get_page();
swap_out(lru_page);
swap_in(vaddr,lru_page);
}
}
void stack_growth(void *vaddr){
uint32_t *paddr,*lru_page;
if ((paddr = palloc_get_page(PAL_ZERO)) != NULL) {
fte_create(paddr, false);
install_page_ext (pg_round_down(vaddr), paddr, true);
set_page_valid(pg_round_down(vaddr), paddr);
}
else
{
lru_page = lru_get_page();
swap_out(lru_page);
set_page_valid(pg_round_down(vaddr), lru_page);
}
}
paddr_t user_page_alloc(){
struct coremap *local_coremap = coremap_list ;
while(local_coremap!=NULL){
if((local_coremap->status & 0x2) == 2 ){
local_coremap->timestamp = localtime;
localtime++;
local_coremap->status = 0 ;
local_coremap->pages=1;
local_coremap->as = curthread->t_addrspace ;
bzero((void *)PADDR_TO_KVADDR(local_coremap->pa),PAGE_SIZE);
return local_coremap->pa;
}
local_coremap = local_coremap->next ;
}
paddr_t pa = swap_out(0) ;
return pa ;
}
/*
* Swap out an object. Only the program is swapped, not the 'object_t'.
*
* marion - the swap seems to corrupt the function table
*/
int swap(object_t * ob)
{
/* the simuls[] table uses pointers to the functions so the simul_efun
* program cannot be relocated. locate_in() could be changed to
* correct this or simuls[] could use offsets, but it doesn't seem
* worth it just to get the simul_efun object to swap. Maybe later.
*
* Ditto the master object and master_applies[]. Mudlibs that have
* a period TIME_TO_SWAP between successive master applies must be
* extremely rare ...
*/
if (ob == simul_efun_ob || ob == master_ob) return 0;
if (ob->flags & O_DESTRUCTED)
return 0;
debug(d_flag, ("Swap object /%s (ref %d)", ob->name, ob->ref));
if (ob->prog->line_info)
swap_line_numbers(ob->prog); /* not always done before we get here */
if ((ob->flags & O_HEART_BEAT) || (ob->flags & O_CLONE)) {
debug(d_flag, (" object not swapped - heart beat or cloned."));
return 0;
}
if (ob->prog->ref > 1 || ob->interactive) {
debug(d_flag, (" object not swapped - inherited or interactive or in apply_low() cache."));
return 0;
}
if (ob->prog->func_ref > 0) {
debug(d_flag, (" object not swapped - referenced by functions."));
return 0;
}
locate_out(ob->prog); /* relocate the internal pointers */
if (swap_out((char *) ob->prog, ob->prog->total_size, (int *) &ob->swap_num)) {
num_swapped++;
free_prog(ob->prog, 0); /* Do not free the strings */
ob->prog = 0;
ob->flags |= O_SWAPPED;
return 1;
} else {
locate_in(ob->prog);
return 0;
}
}
int main(int argc, char *argv[])
{
do
{
prev_ptr = NIL_HOLE;
hp = hole_head;
candidate = hole_head;
last_hole_prev = NIL_HOLE;
while(hp != NIL_HOLE && hp->h_base < swap_base)
{
if(hp->h_len >= clicks && hp->h_len < candidate->h_len)
{
last_hole_prev = prev_ptr;
candidate = hp;
}
prev_ptr = last_hole_prev;
hp = candidate;
last_hole_prev = NIL_HOLE;
}
if (candidate != NIL_HOLE)
{
hp = candidate; prev_ptr = last_hole_prev;
/* We found a hole that is big enough. Use it. */
old_base = hp->h_base; /* remember where it started */
hp->h_base += clicks; /* bite a piece off */
hp->h_len -= clicks; /* ditto */
// Remember new high watermark of used memory.
if(hp->h_base > high_watermark)
high_watermark = hp->h_base;
// Delete the hole if used up completely.
if (hp->h_len == 0) del_slot(prev_ptr, hp);
// Return the start address of the acquired block.
return(old_base);
}
}while(swap_out()); //try to swap out some other process
return(NO_MEM);
}
void *
frame_evict (enum palloc_flags flags)
{
lock_acquire (&frame_table_lock);
struct list_elem *e = list_begin (&frame_table);
while (true) {
struct frame_entry *frame_entry = list_entry (e, struct frame_entry, elem);
struct SP_entry *page_entry = frame_entry->page_entry;
if (!page_entry->pinned) {
struct thread *t = frame_entry->thread;
if (pagedir_is_accessed (t->pagedir, page_entry->page)) {
pagedir_set_accessed (t->pagedir, page_entry->page, false);
} else {
if (pagedir_is_dirty (t->pagedir, page_entry->page) ||
page_entry->type == SP_SWAP) {
if (page_entry->type == SP_MMAP) {
lock_acquire (&filesys_lock);
file_write_at (page_entry->file, frame_entry->frame,
page_entry->read_bytes,
page_entry->offset);
lock_release (&filesys_lock);
} else {
page_entry->type = SP_SWAP;
page_entry->swap_index = swap_out (frame_entry->frame);
}
}
page_entry->is_loaded = false;
list_remove (&frame_entry->elem);
pagedir_clear_page (t->pagedir, page_entry->page);
palloc_free_page (frame_entry->frame);
free (frame_entry);
lock_release (&frame_table_lock);
return palloc_get_page (flags);
}
}
e = list_next (e);
if (e == list_end (&frame_table)) {
e = list_begin (&frame_table);
}
}
}
/*
* Swap out line number information.
*/
int
swap_line_numbers(program_t * prog)
{
int size;
if (!prog || !prog->line_info)
return 0;
debug(d_flag, ("Swap line numbers for /%s", prog->name));
size = prog->file_info[0];
if (swap_out((char *) prog->file_info, size,
&prog->line_swap_index)) {
line_num_bytes_swapped += size;
FREE(prog->file_info);
prog->file_info = 0;
prog->line_info = 0;
return 1;
}
return 0;
}
void *
swap (void)
{
struct frame_entry *victim_frame = find_victim();
struct spage_entry *victim_spage_entry = victim_frame->spe;
uint32_t sectornum = swap_out(victim_frame->frame);
pagedir_clear_page(victim_frame->t->pagedir,victim_spage_entry->uaddr);
victim_spage_entry->indisk = true;
victim_spage_entry->sec_no = sectornum;
palloc_free_page(victim_frame->frame);
falloc_free_frame(victim_frame->frame);
void *kpage = palloc_get_page(PAL_USER|PAL_ZERO);
ASSERT(kpage != NULL);
return kpage;
}
/* The implementation of LRU 'clock' algorithm follows.. we make use of the PTE's accessed bit and dirty bit:
on any read or write to a page ==> accessed bit = 1;
on any write ==> dirty bit = 1;
Step 1: We navigate through the pages in a circular order.. i.e., if we hit the end of the frame list,
we circle back to the start and continue our processing..
Step 2: If the accessed bit is 'accessed', turn it to 'not accessed', skip the page and proceed to look-up the next one in the list
Step 3: If the accessed bit is 'not accessed', we can proceed with our page replacement */
void evict_page() {
struct list_elem *e;
int count = 0;
lock_acquire(&ftable_lock);
for (e = list_begin(&frame_list); e != list_end(&frame_list);
e = list_next(e)) {
struct frame *frame = list_entry(e, struct frame, frame_list_elem);
// printf ("\n%d , %d", count, list_size(&frame_list) - 1);
if (count != list_size(&frame_list) - 1) {
// get the accessed flag for the current page
bool accessed_flag = pagedir_is_accessed(
frame->page->frame_holder_thread->pagedir, frame->page->addr);
if (accessed_flag)
pagedir_set_accessed(frame->page->frame_holder_thread->pagedir,
frame->page->addr, !accessed_flag);
else {
// we need to page replace.. i.e.,
// step 1: remove the existing page from the frame (swap_out call)
// step 2: remove the existing page from the page directory
// step 3: set the accessed flag of the page to 'accessed'
// step 4: free the page and free the frame, for subsequent use
list_remove(e);
swap_out(frame->page);
frame->page->swap_flag = 1;
pagedir_clear_page(frame->page->frame_holder_thread->pagedir,
frame->page->addr);
palloc_free_page(frame->base);
free(frame);
// frame->page->swap_flag = 1;
break;
}
count++;
} else {
count = 0;
e = list_begin(&frame_list);
}
}
lock_release(&ftable_lock);
}
int try_to_free_pages_zone(zone_t *classzone, unsigned int gfp_mask)
{
gfp_mask = pf_gfp_mask(gfp_mask);
for (;;) {
int tries = vm_passes;
int failed_swapout = !(gfp_mask & __GFP_IO);
int nr_pages = SWAP_CLUSTER_MAX;
do {
nr_pages = shrink_caches(classzone, gfp_mask, nr_pages, &failed_swapout);
if (nr_pages <= 0)
return 1;
shrink_dcache_memory(vm_vfs_scan_ratio, gfp_mask);
shrink_icache_memory(vm_vfs_scan_ratio, gfp_mask);
#ifdef CONFIG_QUOTA
shrink_dqcache_memory(vm_vfs_scan_ratio, gfp_mask);
#endif
if (!failed_swapout)
failed_swapout = !swap_out(classzone);
} while (--tries);
#ifdef CONFIG_OOM_KILLER
out_of_memory();
#else
if (likely(current->pid != 1))
break;
if (!check_classzone_need_balance(classzone))
break;
__set_current_state(TASK_RUNNING);
yield();
#endif
}
return 0;
}
/* Evicts the page held in F. */
void evict(struct frame *f) {
uint32_t *pd = thread_current()->pagedir;
ASSERT(lock_held_by_current_thread(&f->evicting));
// lock_acquire(&f->page->moving); /* You should never block here. */
ASSERT(f->page != NULL);
ASSERT(lock_held_by_current_thread(&f->page->moving));
/* Clear page to prevent further writes. */
pagedir_clear_page(f->page->thread->pagedir, f->page->vaddr);
/* If the page had been written to, the changes must be saved. */
if(pagedir_is_dirty(f->page->thread->pagedir, f->page->vaddr)) {
if(f->page->status == PAGE_MAPPED) {
/* If the page is mapped, write changes back to file. */
bool have_lock = lock_held_by_current_thread(&fs_lock);
if(!have_lock)
lock_acquire(&fs_lock);
if(file_write_at(f->page->file, f->addr, f->page->read_bytes, f->page->ofs) != f->page->read_bytes)
PANIC("Didn't write expected %d bytes.", f->page->read_bytes);
if(!have_lock)
lock_release(&fs_lock);
} else {
/* Write page to swap. */
ASSERT(pagedir_is_writeable(f->page->thread->pagedir, f->page->vaddr));
ASSERT(f->page->writeable);
swap_out(f);
}
}
/* Unset link the page and frame. */
f->page->current_frame = NULL;
lock_release(&f->page->moving);
f->page = NULL;
}
static int shrink_cache(int nr_pages, zone_t * classzone, unsigned int gfp_mask, int priority)
{
struct list_head * entry;
int max_scan = nr_inactive_pages / priority;
int max_mapped = min((nr_pages << (10 - priority)), max_scan / 10);
spin_lock(&pagemap_lru_lock);
while (--max_scan >= 0 && (entry = inactive_list.prev) != &inactive_list) {
struct page * page;
/* lock depth is 1 or 2 */
if (unlikely(current->need_resched)) {
spin_unlock(&pagemap_lru_lock);
__set_current_state(TASK_RUNNING);
schedule();
spin_lock(&pagemap_lru_lock);
continue;
}
page = list_entry(entry, struct page, lru);
if (unlikely(!PageLRU(page)))
BUG();
if (unlikely(PageActive(page)))
BUG();
list_del(entry);
list_add(entry, &inactive_list);
/*
* Zero page counts can happen because we unlink the pages
* _after_ decrementing the usage count..
*/
if (unlikely(!page_count(page)))
continue;
if (!memclass(page->zone, classzone))
continue;
/* Racy check to avoid trylocking when not worthwhile */
if (!page->buffers && (page_count(page) != 1 || !page->mapping))
goto page_mapped;
/*
* The page is locked. IO in progress?
* Move it to the back of the list.
*/
if (unlikely(TryLockPage(page))) {
if (PageLaunder(page) && (gfp_mask & __GFP_FS)) {
page_cache_get(page);
spin_unlock(&pagemap_lru_lock);
wait_on_page(page);
page_cache_release(page);
spin_lock(&pagemap_lru_lock);
}
continue;
}
if ((PageDirty(page) || DelallocPage(page)) && is_page_cache_freeable(page) && page->mapping) {
/*
* It is not critical here to write it only if
* the page is unmapped beause any direct writer
* like O_DIRECT would set the PG_dirty bitflag
* on the phisical page after having successfully
* pinned it and after the I/O to the page is finished,
* so the direct writes to the page cannot get lost.
*/
int (*writepage)(struct page *);
writepage = page->mapping->a_ops->writepage;
if ((gfp_mask & __GFP_FS) && writepage) {
ClearPageDirty(page);
SetPageLaunder(page);
page_cache_get(page);
spin_unlock(&pagemap_lru_lock);
writepage(page);
page_cache_release(page);
spin_lock(&pagemap_lru_lock);
continue;
}
}
/*
* If the page has buffers, try to free the buffer mappings
* associated with this page. If we succeed we try to free
* the page as well.
*/
if (page->buffers) {
spin_unlock(&pagemap_lru_lock);
/* avoid to free a locked page */
page_cache_get(page);
if (try_to_release_page(page, gfp_mask)) {
if (!page->mapping) {
/*
* We must not allow an anon page
* with no buffers to be visible on
* the LRU, so we unlock the page after
* taking the lru lock
*/
spin_lock(&pagemap_lru_lock);
UnlockPage(page);
__lru_cache_del(page);
/* effectively free the page here */
page_cache_release(page);
if (--nr_pages)
continue;
break;
} else {
/*
* The page is still in pagecache so undo the stuff
* before the try_to_release_page since we've not
* finished and we can now try the next step.
*/
page_cache_release(page);
spin_lock(&pagemap_lru_lock);
}
} else {
/* failed to drop the buffers so stop here */
UnlockPage(page);
page_cache_release(page);
spin_lock(&pagemap_lru_lock);
continue;
}
}
spin_lock(&pagecache_lock);
/*
* this is the non-racy check for busy page.
*/
if (!page->mapping || !is_page_cache_freeable(page)) {
spin_unlock(&pagecache_lock);
UnlockPage(page);
page_mapped:
if (--max_mapped >= 0)
continue;
/*
* Alert! We've found too many mapped pages on the
* inactive list, so we start swapping out now!
*/
spin_unlock(&pagemap_lru_lock);
swap_out(priority, gfp_mask, classzone);
return nr_pages;
}
/*
* It is critical to check PageDirty _after_ we made sure
* the page is freeable* so not in use by anybody.
*/
if (PageDirty(page)) {
spin_unlock(&pagecache_lock);
UnlockPage(page);
continue;
}
/* point of no return */
if (likely(!PageSwapCache(page))) {
__remove_inode_page(page);
spin_unlock(&pagecache_lock);
} else {
swp_entry_t swap;
swap.val = page->index;
__delete_from_swap_cache(page);
spin_unlock(&pagecache_lock);
swap_free(swap);
}
__lru_cache_del(page);
UnlockPage(page);
/* effectively free the page here */
page_cache_release(page);
if (--nr_pages)
continue;
break;
}
spin_unlock(&pagemap_lru_lock);
return nr_pages;
}
static int shrink_cache(int nr_pages, zone_t * classzone, unsigned int gfp_mask, int * failed_swapout)
{
struct list_head * entry;
int max_scan = (classzone->nr_inactive_pages + classzone->nr_active_pages) / vm_cache_scan_ratio;
int max_mapped = vm_mapped_ratio * nr_pages;
while (max_scan && classzone->nr_inactive_pages && (entry = inactive_list.prev) != &inactive_list) {
struct page * page;
if (unlikely(current->need_resched)) {
spin_unlock(&pagemap_lru_lock);
__set_current_state(TASK_RUNNING);
schedule();
spin_lock(&pagemap_lru_lock);
continue;
}
page = list_entry(entry, struct page, lru);
BUG_ON(!PageLRU(page));
BUG_ON(PageActive(page));
list_del(entry);
list_add(entry, &inactive_list);
/*
* Zero page counts can happen because we unlink the pages
* _after_ decrementing the usage count..
*/
if (unlikely(!page_count(page)))
continue;
if (!memclass(page_zone(page), classzone))
continue;
max_scan--;
/* Racy check to avoid trylocking when not worthwhile */
if (!page->buffers && (page_count(page) != 1 || !page->mapping))
goto page_mapped;
/*
* The page is locked. IO in progress?
* Move it to the back of the list.
*/
if (unlikely(TryLockPage(page))) {
if (PageLaunder(page) && (gfp_mask & __GFP_FS)) {
page_cache_get(page);
spin_unlock(&pagemap_lru_lock);
wait_on_page(page);
page_cache_release(page);
spin_lock(&pagemap_lru_lock);
}
continue;
}
if (PageDirty(page) && is_page_cache_freeable(page) && page->mapping) {
/*
* It is not critical here to write it only if
* the page is unmapped beause any direct writer
* like O_DIRECT would set the PG_dirty bitflag
* on the phisical page after having successfully
* pinned it and after the I/O to the page is finished,
* so the direct writes to the page cannot get lost.
*/
int (*writepage)(struct page *);
writepage = page->mapping->a_ops->writepage;
if ((gfp_mask & __GFP_FS) && writepage) {
ClearPageDirty(page);
SetPageLaunder(page);
page_cache_get(page);
spin_unlock(&pagemap_lru_lock);
writepage(page);
page_cache_release(page);
spin_lock(&pagemap_lru_lock);
continue;
}
}
/*
* If the page has buffers, try to free the buffer mappings
* associated with this page. If we succeed we try to free
* the page as well.
*/
if (page->buffers) {
spin_unlock(&pagemap_lru_lock);
/* avoid to free a locked page */
page_cache_get(page);
if (try_to_release_page(page, gfp_mask)) {
if (!page->mapping) {
/*
* We must not allow an anon page
* with no buffers to be visible on
* the LRU, so we unlock the page after
* taking the lru lock
*/
spin_lock(&pagemap_lru_lock);
UnlockPage(page);
__lru_cache_del(page);
/* effectively free the page here */
page_cache_release(page);
if (--nr_pages)
continue;
break;
} else {
/*
* The page is still in pagecache so undo the stuff
* before the try_to_release_page since we've not
* finished and we can now try the next step.
*/
page_cache_release(page);
spin_lock(&pagemap_lru_lock);
}
} else {
/* failed to drop the buffers so stop here */
UnlockPage(page);
page_cache_release(page);
spin_lock(&pagemap_lru_lock);
continue;
}
}
spin_lock(&pagecache_lock);
/*
* This is the non-racy check for busy page.
* It is critical to check PageDirty _after_ we made sure
* the page is freeable so not in use by anybody.
* At this point we're guaranteed that page->buffers is NULL,
* nobody can refill page->buffers under us because we still
* hold the page lock.
*/
if (!page->mapping || page_count(page) > 1) {
spin_unlock(&pagecache_lock);
UnlockPage(page);
page_mapped:
if (--max_mapped < 0) {
spin_unlock(&pagemap_lru_lock);
nr_pages -= kmem_cache_reap(gfp_mask);
if (nr_pages <= 0)
goto out;
shrink_dcache_memory(vm_vfs_scan_ratio, gfp_mask);
shrink_icache_memory(vm_vfs_scan_ratio, gfp_mask);
#ifdef CONFIG_QUOTA
shrink_dqcache_memory(vm_vfs_scan_ratio, gfp_mask);
#endif
if (!*failed_swapout)
*failed_swapout = !swap_out(classzone);
max_mapped = nr_pages * vm_mapped_ratio;
spin_lock(&pagemap_lru_lock);
refill_inactive(nr_pages, classzone);
}
continue;
}
if (PageDirty(page)) {
spin_unlock(&pagecache_lock);
UnlockPage(page);
continue;
}
__lru_cache_del(page);
/* point of no return */
if (likely(!PageSwapCache(page))) {
__remove_inode_page(page);
spin_unlock(&pagecache_lock);
} else {
swp_entry_t swap;
swap.val = page->index;
__delete_from_swap_cache(page);
spin_unlock(&pagecache_lock);
swap_free(swap);
}
UnlockPage(page);
/* effectively free the page here */
page_cache_release(page);
if (--nr_pages)
continue;
break;
}
spin_unlock(&pagemap_lru_lock);
out:
return nr_pages;
}
/*
* We need to make the locks finer granularity, but right
* now we need this so that we can do page allocations
* without holding the kernel lock etc.
*
* We want to try to free "count" pages, and we want to
* cluster them so that we get good swap-out behaviour.
*
* OTOH, if we're a user process (and not kswapd), we
* really care about latency. In that case we don't try
* to free too many pages.
*/
static int refill_inactive(unsigned int gfp_mask, int user)
{
int priority, count, start_count, made_progress;
unsigned long idle_time;
count = inactive_shortage() + free_shortage();
if (user)
count = (1 << page_cluster);
start_count = count;
/* Always trim SLAB caches when memory gets low. */
kmem_cache_reap(gfp_mask);
/*
* Calculate the minimum time (in seconds) a process must
* have slept before we consider it for idle swapping.
* This must be the number of seconds it takes to go through
* all of the cache. Doing this idle swapping makes the VM
* smoother once we start hitting swap.
*/
idle_time = atomic_read(&page_cache_size);
idle_time += atomic_read(&buffermem_pages);
idle_time /= (inactive_target + 1);
priority = 6;
do {
made_progress = 0;
if (current->need_resched) {
__set_current_state(TASK_RUNNING);
schedule();
}
while (refill_inactive_scan(priority, 1) ||
swap_out(priority, gfp_mask, idle_time)) {
made_progress = 1;
if (--count <= 0)
goto done;
}
/*
* don't be too light against the d/i cache since
* refill_inactive() almost never fail when there's
* really plenty of memory free.
*/
shrink_dcache_memory(priority, gfp_mask);
shrink_icache_memory(priority, gfp_mask);
/*
* Then, try to page stuff out..
*/
while (swap_out(priority, gfp_mask, 0)) {
made_progress = 1;
if (--count <= 0)
goto done;
}
/*
* If we either have enough free memory, or if
* page_launder() will be able to make enough
* free memory, then stop.
*/
if (!inactive_shortage() || !free_shortage())
goto done;
/*
* Only switch to a lower "priority" if we
* didn't make any useful progress in the
* last loop.
*/
if (!made_progress)
priority--;
} while (priority >= 0);
/* Always end on a refill_inactive.., may sleep... */
while (refill_inactive_scan(0, 1)) {
if (--count <= 0)
goto done;
}
done:
return (count < start_count);
}