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static unsigned long isolate_lru_pages(unsigned longnr_to_scan,
struct lruvec *lruvec, struct list_head*dst,
unsignedlong *nr_scanned, struct scan_control *sc,
isolate_mode_tmode, enum lru_list lru)
{
struct list_head *src = &lruvec->lists[lru];
unsignedlong nr_taken = 0;
unsignedlong scan;
for (scan=0;scan<nr_to_scan&& nr_taken < nr_to_scan &&!list_empty(src); scan++) {
structpage *page;
page= lru_to_page(src);
prefetchw_prev_lru_page(page,src, flags);
VM_BUG_ON_PAGE(!PageLRU(page),page);
switch(__isolate_lru_page(page, mode)) {
case0:
nr_taken+= hpage_nr_pages(page);
list_move(&page->lru,dst);
break;
case-EBUSY:
/*else it is being freed elsewhere */
list_move(&page->lru,src);
continue;
default:
BUG();
}
}
*nr_scanned = scan;
trace_mm_vmscan_lru_isolate(sc->order,nr_to_scan, scan, nr_taken, mode, is_file_lru(lru));
return nr_taken;
}
int __isolate_lru_page(struct page *page, isolate_mode_t mode)
{
intret = -EINVAL;
/*Only take pages on the LRU. */
if (!PageLRU(page))
returnret;
/*Compaction should not handle unevictable pages but CMA can do so */
if(PageUnevictable(page) && !(mode &ISOLATE_UNEVICTABLE))
returnret;
ret= -EBUSY;
if(mode & (ISOLATE_CLEAN|ISOLATE_ASYNC_MIGRATE)) {
/*All the caller can do on PageWriteback is block */
if (PageWriteback(page))
returnret;
if (PageDirty(page)) {
structaddress_space *mapping;
/*ISOLATE_CLEAN means only clean pages */
if (mode & ISOLATE_CLEAN)
returnret;
mapping = page_mapping(page);
if(mapping && !mapping->a_ops->migratepage)
returnret;
}
}
if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))
returnret;
if (likely(get_page_unless_zero(page))) {
ClearPageLRU(page);
ret= 0;
}
return ret;
}
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