On Wed 01-05-19 23:49:10, Dexuan Cui wrote:
> Hi,
> Today I got the below BUG in isolate_lru_pages() when building the kernel.
>
> My current running kernel, which exhibits the BUG, is based on the mainline kernel's commit
> 262d6a9a63a3 ("Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip").
>
> Looks nobody else reported the issue recently.
>
> So far I only hit the BUG once and I don't know how to reproduce it again, so this is just a FYI.
This is really unexpected. This BUG means that __isolate_lru_page must
have returned EINVAL which implies a non-LRU page on the LRU or an
unevictable page on an evictable LRU list. I am currently travelling so
I cannot have deeper look. There was a similar report which triggered a
different BUG_ON in the reclaim path also stumbling over but that was on
an really old kernel with out of tree patches so it is not clear what
happened there. Do you think it would be possible to setup a crash dump
or apply the following debugging patch in case it reproduces?
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a5ad0b35ab8e..289493986f6c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1686,6 +1686,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
continue;
default:
+ dump_page(page);
BUG();
}
}
Thanks for the report.
--
Michal Hocko
SUSE Labs
