On Mon, Mar 06, 2017 at 11:15:08AM +0900, Minchan Kim wrote: > Hi Anshuman, > > On Fri, Mar 03, 2017 at 06:06:38PM +0530, Anshuman Khandual wrote: > > On 03/02/2017 12:09 PM, Minchan Kim wrote: > > > ttu don't need to return SWAP_MLOCK. Instead, just return SWAP_FAIL > > > because it means the page is not-swappable so it should move to > > > another LRU list(active or unevictable). putback friends will > > > move it to right list depending on the page's LRU flag. > > > > Right, if it cannot be swapped out there is not much difference with > > SWAP_FAIL once we change the callers who expected to see a SWAP_MLOCK > > return instead. > > > > > > > > A side effect is shrink_page_list accounts unevictable list movement > > > by PGACTIVATE but I don't think it corrupts something severe. > > > > Not sure I got that, could you please elaborate on this. We will still > > activate the page and put it in an appropriate LRU list if it is marked > > mlocked ? > > Right. putback_iactive_pages/putback_lru_page has a logic to filter > out unevictable pages and move them to unevictable LRU list so it > doesn't break LRU change behavior but the concern is until now, > we have accounted PGACTIVATE for only evictable LRU list page but > by this change, it accounts it to unevictable LRU list as well. > However, although I don't think it's big problem in real practice, > we can fix it simply with checking PG_mlocked if someone reports. I think it's better to do this pro-actively. Let's hide both pgactivate++ and SetPageActive() under "if (!PageMlocked())". SetPageActive() is not free. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
