From: Michal Hocko <mhocko@kernel.org>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Stephen Rothwell <sfr@canb.auug.org.au>,
linux-mm@kvack.org, linux-next@vger.kernel.org,
linux-kernel@vger.kernel.org,
Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [linux-next: Tree for Jun 1] __khugepaged_exit rwsem_down_write_failed lockup
Date: Fri, 3 Jun 2016 11:55:49 +0200 [thread overview]
Message-ID: <20160603095549.GD20676@dhcp22.suse.cz> (raw)
In-Reply-To: <20160603084347.GA502@swordfish>
On Fri 03-06-16 17:43:47, Sergey Senozhatsky wrote:
> On (06/03/16 09:25), Michal Hocko wrote:
> > > it's quite hard to trigger the bug (somehow), so I can't
> > > follow up with more information as of now.
>
> either I did something very silly fixing up the patch, or the
> patch may be causing general protection faults on my system.
>
> RIP collect_mm_slot() + 0x42/0x84
> khugepaged
So is this really collect_mm_slot called directly from khugepaged or is
some inlining going on there?
> prepare_to_wait_event
> maybe_pmd_mkwrite
> kthread
> _raw_sin_unlock_irq
> ret_from_fork
> kthread_create_on_node
>
> collect_mm_slot() + 0x42/0x84 is
I guess that the problem is that I have missed that __khugepaged_exit
doesn't clear the cached khugepaged_scan.mm_slot. Does the following on
top fixes that?
---
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6574c62ca4a3..e6f4e6fd587a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2021,6 +2021,8 @@ void __khugepaged_exit(struct mm_struct *mm)
spin_lock(&khugepaged_mm_lock);
mm_slot = get_mm_slot(mm);
if (mm_slot) {
+ if (khugepaged_scan.mm_slot == mm_slot)
+ khugepaged_scan.mm_slot = NULL;
collect_mm_slot(mm_slot);
clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
}
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2016-06-03 9:55 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-01 3:11 linux-next: Tree for Jun 1 Stephen Rothwell
2016-06-02 1:48 ` [linux-next: Tree for Jun 1] __khugepaged_exit rwsem_down_write_failed lockup Sergey Senozhatsky
2016-06-02 9:21 ` Michal Hocko
2016-06-02 12:08 ` Sergey Senozhatsky
2016-06-02 12:21 ` Michal Hocko
2016-06-03 13:51 ` Andrea Arcangeli
2016-06-03 14:46 ` Michal Hocko
2016-06-03 15:10 ` Andrea Arcangeli
2016-06-07 7:34 ` Michal Hocko
2016-06-08 8:19 ` Vlastimil Babka
2016-06-03 7:15 ` Sergey Senozhatsky
2016-06-03 7:25 ` Michal Hocko
2016-06-03 8:43 ` Sergey Senozhatsky
2016-06-03 9:55 ` Michal Hocko [this message]
2016-06-03 10:05 ` Michal Hocko
2016-06-03 13:38 ` Sergey Senozhatsky
2016-06-03 13:45 ` Michal Hocko
2016-06-03 13:49 ` Michal Hocko
2016-06-04 7:51 ` Sergey Senozhatsky
2016-06-06 8:39 ` Michal Hocko
2016-06-02 13:24 ` Vlastimil Babka
2016-06-02 18:58 ` Ebru Akagunduz
2016-06-03 1:00 ` Sergey Senozhatsky
2016-06-03 1:29 ` Sergey Senozhatsky
2016-06-03 4:14 ` Sergey Senozhatsky
2016-06-03 12:28 ` [PATCH] mm, thp: fix locking inconsistency in collapse_huge_page Ebru Akagunduz
2016-06-06 13:05 ` Vlastimil Babka
2016-06-09 3:51 ` Sergey Senozhatsky
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