Hi Miao, On Sun, 27 Mar 2011 15:00:00 +0800 Miao Xie <miaox@xxxxxxxxxxxxxx> wrote: > I got it. It is because the allocation flag of the metadata's page cache, which is stored in > the btree inode's i_mapping, was set to be GFP_HIGHUSER_MOVABLE. So if we allocate pages for > btree's page cache, this lockdep warning will be triggered. > > I think even without my patch, this lockdep warning can also be triggered, btrfs_evict_inode() > do the similar operations like what I do in the btrfs_destroy_inode(). > Task1 Kswap0 task > open() > ... > btrfs_search_slot() > ... > btrfs_cow_block() > ... > alloc_page() > wait for reclaiming > shrink_slab() > ... > shrink_icache_memory() > ... > btrfs_evict_inode() > ... > btrfs_search_slot() > > If the path is locked by task1, the deadlock happens. Ok. balance_pgdat() calls shrink_slab() with GFP_KERNEL so it's still possible for the kswapd0 to call prune_icache(), no? I still see the lockdep warning even with your patch that clears __GFP_FS in open_ctree(). itaru -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
