lkml.org 
[lkml]   [2016]   [Jun]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [mmots-2016-06-09-16-49] kernel BUG at mm/slub.c:1616
On Fri 10-06-16 16:24:59, Sergey Senozhatsky wrote:
> that was fast!
>
> On (06/10/16 08:34), Michal Hocko wrote:
> [..]
> > OK, so this is flags & GFP_SLAB_BUG_MASK BUG_ON because gfp is
> > ___GFP_HIGHMEM. It is my [1] patch which has introduced it.
> > I think we need the following. Andrew could you fold it into
> > mm-memcg-use-consistent-gfp-flags-during-readahead.patch or maybe keep
> > it as a separate patch?
> >
> > [1] http://lkml.kernel.org/r/1465301556-26431-1-git-send-email-mhocko@kernel.org
> >
> > Thanks for the report Sergey!
>
> after quick tests -- works for me. please see below.
[...]
> so the first bio_alloc() is ok now. what about the second bio_alloc()
> in mpage_alloc()? it'll still see the ___GFP_HIGHMEM?

Sure, early morning for me... Thanks for catching that.
---
From a2712312c0a36506ba003747c593dfbdf8eaa8be Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Fri, 10 Jun 2016 08:27:33 +0200
Subject: [PATCH] mm: restrict gfp mask in mpage_alloc

Sergey has reported that we might hit BUG_ON in new_slab() because
unrestricted gfp mask used for the readahead purposes contains
incompatible flags (__GFP_HIGHMEM in his case):
[ 429.191962] gfp: 2
[ 429.192634] ------------[ cut here ]------------
[ 429.193281] kernel BUG at mm/slub.c:1616!
[...]
[ 429.217369] [<ffffffff811ca221>] bio_alloc_bioset+0xbd/0x1b1
[ 429.218013] [<ffffffff81148078>] mpage_alloc+0x28/0x7b
[ 429.218650] [<ffffffff8114856a>] do_mpage_readpage+0x43d/0x545
[ 429.219282] [<ffffffff81148767>] mpage_readpages+0xf5/0x152

Make sure that mpage_alloc always restricts the mask to GFP_KERNEL subset.
This is what was done before "mm, memcg: use consistent gfp flags during
readahead" explicitly by mapping_gfp_constraint(mapping, GFP_KERNEL) in
mpage_readpages.

Reported-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
fs/mpage.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/fs/mpage.c b/fs/mpage.c
index 9c11255b0797..c8a05901a37b 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -71,6 +71,8 @@ mpage_alloc(struct block_device *bdev,
{
struct bio *bio;

+ /* Restrict the given (page cache) mask for slab allocations */
+ gfp_flags &= GFP_KERNEL;
bio = bio_alloc(gfp_flags, nr_vecs);

if (bio == NULL && (current->flags & PF_MEMALLOC)) {
--
2.8.1
--
Michal Hocko
SUSE Labs

\
 
 \ /
  Last update: 2016-06-10 10:21    [W:0.059 / U:0.124 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site