On 06/02/2013 10:40 PM, Minchan Kim wrote: >> > diff -puN mm/vmscan.c~__delete_from_swap_cache-dont-clear-page-private >> > mm/vmscan.c >> > --- linux.git/mm/vmscan.c~__delete_from_swap_cache-dont-clear-page-private >> > 2013-05-30 16:07:50.632079492 -0700 >> > +++ linux.git-davehans/mm/vmscan.c 2013-05-30 16:07:50.637079712 -0700 >> > @@ -494,6 +494,8 @@ static int __remove_mapping(struct addre >> > __delete_from_swap_cache(page); >> > spin_unlock_irq(&mapping->tree_lock); >> > swapcache_free(swap, page); >> > + set_page_private(page, 0); >> > + ClearPageSwapCache(page); > It it worth to support non-atomic version of ClearPageSwapCache?
Just for this, probably not. It does look like a site where it would be theoretically safe to use non-atomic flag operations since the page is on a one-way trip to the allocator at this point and the __clear_page_locked() now happens _just_ after this code. But, personally, I'm happy to leave it as-is. The atomic vs. non-atomic flags look to me like a micro-optimization that we should use when we _know_ there will be some tangible benefit. Otherwise, they're just something extra for developers to trip over and cause very subtle bugs. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
