We ->put_page() into tcache twice w/o ->get_page() in between, resulting in:
WARNING: CPU: 1 PID: 1936 at mm/tcache.c:752 tcache_attach_page+0x218/0x240 Call Trace: dump_stack+0x19/0x1b add_taint+0x32/0x70 __warn+0xaa/0x100 warn_slowpath_null+0x1d/0x20 tcache_attach_page+0x218/0x240 tcache_cleancache_put_page+0xdc/0x150 __cleancache_put_page+0xa2/0xf0 __delete_from_page_cache+0x309/0x370 __remove_mapping+0x91/0x180 shrink_page_list+0x5a8/0xa80 shrink_inactive_list+0x1da/0x710 shrink_lruvec+0x3a1/0x760 shrink_zone+0x15b/0x310 do_try_to_free_pages+0x1a0/0x610 try_to_free_mem_cgroup_pages+0xeb/0x190 mem_cgroup_reclaim+0x63/0x140 try_charge+0x287/0x560 mem_cgroup_try_charge+0x7a/0x130 __add_to_page_cache_locked+0x97/0x2f0 add_to_page_cache_lru+0x37/0xb0 mpage_readpages+0xb5/0x150 ext4_readpages+0x3c/0x40 [ext4] __do_page_cache_readahead+0x1cd/0x250 ondemand_readahead+0x116/0x230 page_cache_async_readahead+0xa8/0xc0 It's because we put all clean pages into cleancache, but in some cases we may never read those pages from cleancache. E.g. see do_mpage_readpage(), there are many case when cleancache_get_page() is not called. Fix this by invalidating such existing page during ->put_page(). https://jira.sw.ru/browse/PSBM-80712 Reported-by: Kirill Tkhai <ktk...@virtuozzo.com> Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> --- mm/tcache.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/mm/tcache.c b/mm/tcache.c index a45af63fbd1b..76e34d7e8851 100644 --- a/mm/tcache.c +++ b/mm/tcache.c @@ -749,7 +749,6 @@ static int tcache_page_tree_insert(struct tcache_node *node, pgoff_t index, } err = radix_tree_insert(&node->page_tree, index, page); - WARN_ON(err == -EEXIST); if (!err) { if (!node->nr_pages++) tcache_hold_node(node); @@ -1256,7 +1255,15 @@ static int tcache_cleancache_put_page(int pool_id, cache_page = tcache_alloc_page(node->pool); if (cache_page) { copy_highpage(cache_page, page); - if (tcache_attach_page(node, index, cache_page)) { + ret = tcache_attach_page(node, index, cache_page); + if (ret) { + if (ret == -EEXIST) { + struct page *page; + + page = tcache_detach_page(node, index, false); + if (page) + tcache_put_page(page); + } if (put_page_testzero(cache_page)) tcache_put_page(cache_page); } else -- 2.13.6 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
