Hi Mel,
I'm chasing an apparent memory leak introduced post-3.6. The
interesting thing is that it appears that the pages are in the
allocator, but not being accounted for:
http://www.spinics.net/lists/linux-mm/msg46187.html
https://bugzilla.kernel.org/show_bug.cgi?id=50181
I started auditing anything that might be messing with NR_FREE_PAGES,
and came across commit 1fb3f8ca. It does something curious with
capture_free_page() (previously known as split_free_page()).
int capture_free_page(struct page *page, int alloc_order,
...
__mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order));
- /* Split into individual pages */
- set_page_refcounted(page);
- split_page(page, order);
+ if (alloc_order != order)
+ expand(zone, page, alloc_order, order,
+ &zone->free_area[order], migratetype);
Note that expand() puts the pages _back_ in the allocator, but it does
not bump NR_FREE_PAGES. We "return" alloc_order' worth of pages, but we
accounted for removing 'order'.
I _think_ the correct fix is to just:
- __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order));
+ __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << alloc_order));
I'm trying to confirm the theory my making this happen a bit more often,
but I'd appreciate a second pair of eyes on the code in case I'm reading
it wrong.
--
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/
