On 05/11/2013 06:23 PM, Kirill A. Shutemov wrote: > From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> > > active/inactive lru lists can contain unevicable pages (i.e. ramfs pages > that have been placed on the LRU lists when first allocated), but these > pages must not have PageUnevictable set - otherwise shrink_active_list > goes crazy: > > kernel BUG at /home/space/kas/git/public/linux-next/mm/vmscan.c:1122! > invalid opcode: 0000 [#1] SMP > CPU 0 > Pid: 293, comm: kswapd0 Not tainted 3.8.0-rc6-next-20130202+ #531 > RIP: 0010:[<ffffffff81110478>] [<ffffffff81110478>] isolate_lru_pages.isra.61+0x138/0x260 > RSP: 0000:ffff8800796d9b28 EFLAGS: 00010082' ... I'd much rather see a code snippet and description the BUG_ON() than a register and stack dump. That line number is wrong already. ;) > For lru_add_page_tail(), it means we should not set PageUnevictable() > for tail pages unless we're sure that it will go to LRU_UNEVICTABLE. > Let's just copy PG_active and PG_unevictable from head page in > __split_huge_page_refcount(), it will simplify lru_add_page_tail(). > > This will fix one more bug in lru_add_page_tail(): > if page_evictable(page_tail) is false and PageLRU(page) is true, page_tail > will go to the same lru as page, but nobody cares to sync page_tail > active/inactive state with page. So we can end up with inactive page on > active lru. > The patch will fix it as well since we copy PG_active from head page. This all seems good, and if it fixes a bug, it should really get merged as it stands. Have you been actually able to trigger that bug in any way in practice? Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
