Hi all, A small piece of code in mm/vmscan.c kept me confused. Please
could some one explain this ?
File: mm/vmscan.c , try_to_swap_out()
....SNIP....
drop_pte: mm->rss--
UnlockPage(page);
---SNIP--
page_cache_release(page);
return freeable;
----SNIP----
if(page->mapping)
goto drop_pte;
What i can get is if page->mapping is NOT NULL , then do a
page_cache_release(). This boils down to __free_pages_ok(). Here the
code snippet is if(page->mapping) BUG();
So if try_to_swap_out wants to drop a page which can be brought in
always ( i.e , not dirty ), then what is the harm in setting it to NULL ?
TIA
Bourne