From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: linux-mm@kvack.org, kamezawa.hiroyu@jp.fujitsu.com,
dhillf@gmail.com, rientjes@google.com, mhocko@suse.cz,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org
Subject: Re: [PATCH -V8 05/16] hugetlb: avoid taking i_mmap_mutex in unmap_single_vma() for hugetlb
Date: Sat, 09 Jun 2012 18:33:05 +0530 [thread overview]
Message-ID: <87sje4ljsm.fsf@skywalker.in.ibm.com> (raw)
In-Reply-To: <20120609094444.GG1761@cmpxchg.org>
Johannes Weiner <hannes@cmpxchg.org> writes:
> On Sat, Jun 09, 2012 at 02:29:50PM +0530, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>>
>> i_mmap_mutex lock was added in unmap_single_vma by 502717f4e ("hugetlb:
>> fix linked list corruption in unmap_hugepage_range()") but we don't use
>> page->lru in unmap_hugepage_range any more. Also the lock was taken
>> higher up in the stack in some code path. That would result in deadlock.
>>
>> unmap_mapping_range (i_mmap_mutex)
>> -> unmap_mapping_range_tree
>> -> unmap_mapping_range_vma
>> -> zap_page_range_single
>> -> unmap_single_vma
>> -> unmap_hugepage_range (i_mmap_mutex)
>>
>> For shared pagetable support for huge pages, since pagetable pages are ref
>> counted we don't need any lock during huge_pmd_unshare. We do take
>> i_mmap_mutex in huge_pmd_share while walking the vma_prio_tree in mapping.
>> (39dde65c9940c97f ("shared page table for hugetlb page")).
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>
> This patch (together with the previous one) seems like a bugfix that's
> not really related to the hugetlb controller, unless I miss something.
>
> Could you please submit the fix separately?
Patches upto 6 can really got in a separate series. I was not sure
whether I should split them. I will post that as a separate series now
>
> Maybe also fold the two patches into one and make it a single bugfix
> change that gets rid of the lock by switching away from page->lru.
I wanted to make sure the patch that drop i_mmap_mutex is a separate one
so that we understand and document the locking details separately
-aneesh
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next prev parent reply other threads:[~2012-06-09 13:03 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-09 8:59 [PATCH -V8 00/16] hugetlb: Add HugeTLB controller to control HugeTLB allocation Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 01/16] hugetlb: rename max_hstate to hugetlb_max_hstate Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 02/16] hugetlb: don't use ERR_PTR with VM_FAULT* values Aneesh Kumar K.V
2012-06-09 11:10 ` Konrad Rzeszutek Wilk
2012-06-09 13:17 ` Aneesh Kumar K.V
2012-06-09 19:28 ` KOSAKI Motohiro
2012-06-10 1:59 ` Hillf Danton
2012-06-09 8:59 ` [PATCH -V8 03/16] hugetlb: add an inline helper for finding hstate index Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 04/16] hugetlb: use mmu_gather instead of a temporary linked list for accumulating pages Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 05/16] hugetlb: avoid taking i_mmap_mutex in unmap_single_vma() for hugetlb Aneesh Kumar K.V
2012-06-09 9:44 ` Johannes Weiner
2012-06-09 13:03 ` Aneesh Kumar K.V [this message]
2012-06-09 14:49 ` Johannes Weiner
2012-06-09 8:59 ` [PATCH -V8 06/16] hugetlb: simplify migrate_huge_page() Aneesh Kumar K.V
2012-06-12 7:31 ` Kamezawa Hiroyuki
2012-06-09 8:59 ` [PATCH -V8 07/16] hugetlb: add a list for tracking in-use HugeTLB pages Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 08/16] hugetlb: Make some static variables global Aneesh Kumar K.V
2012-06-12 7:35 ` Kamezawa Hiroyuki
2012-06-09 8:59 ` [PATCH -V8 09/16] mm/hugetlb: Add new HugeTLB cgroup Aneesh Kumar K.V
2012-06-12 7:46 ` Kamezawa Hiroyuki
2012-06-12 9:37 ` Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 10/16] hugetlb/cgroup: Add the cgroup pointer to page lru Aneesh Kumar K.V
2012-06-09 11:14 ` Konrad Rzeszutek Wilk
2012-06-09 17:04 ` Aneesh Kumar K.V
2012-06-11 8:16 ` Michal Hocko
2012-06-11 9:03 ` Aneesh Kumar K.V
2012-06-11 9:16 ` Michal Hocko
2012-06-11 9:33 ` Aneesh Kumar K.V
2012-06-11 8:41 ` Kamezawa Hiroyuki
2012-06-12 7:52 ` Kamezawa Hiroyuki
2012-06-12 9:40 ` Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 11/16] hugetlb/cgroup: Add charge/uncharge routines for hugetlb cgroup Aneesh Kumar K.V
2012-06-11 8:38 ` Michal Hocko
2012-06-11 9:10 ` Michal Hocko
2012-06-11 9:28 ` Aneesh Kumar K.V
2012-06-11 12:59 ` Michal Hocko
2012-06-11 15:35 ` Aneesh Kumar K.V
2012-06-12 8:08 ` Kamezawa Hiroyuki
2012-06-12 10:50 ` Aneesh Kumar K.V
2012-06-13 11:02 ` Kamezawa Hiroyuki
2012-06-09 8:59 ` [PATCH -V8 12/16] hugetlb/cgroup: Add support for cgroup removal Aneesh Kumar K.V
2012-06-11 8:52 ` Michal Hocko
2012-06-11 9:40 ` Aneesh Kumar K.V
2012-06-11 13:14 ` Michal Hocko
2012-06-11 15:34 ` Aneesh Kumar K.V
2012-06-12 8:23 ` Kamezawa Hiroyuki
2012-06-12 10:52 ` Aneesh Kumar K.V
2012-06-09 8:59 ` [PATCH -V8 13/16] hugetlb/cgroup: add hugetlb cgroup control files Aneesh Kumar K.V
2012-06-09 11:19 ` Konrad Rzeszutek Wilk
2012-06-11 9:02 ` Michal Hocko
2012-06-11 9:43 ` Aneesh Kumar K.V
2012-06-11 13:15 ` Michal Hocko
2012-06-12 8:35 ` Kamezawa Hiroyuki
2012-06-12 10:58 ` Aneesh Kumar K.V
2012-06-13 0:16 ` Kamezawa Hiroyuki
2012-06-09 8:59 ` [PATCH -V8 14/16] hugetlb/cgroup: add charge/uncharge calls for HugeTLB alloc/free Aneesh Kumar K.V
2012-06-09 9:23 ` Johannes Weiner
2012-06-09 13:09 ` Aneesh Kumar K.V
2012-06-09 14:30 ` Johannes Weiner
2012-06-09 15:55 ` Aneesh Kumar K.V
2012-06-11 9:19 ` Michal Hocko
2012-06-11 9:21 ` Michal Hocko
2012-06-11 10:29 ` Aneesh Kumar K.V
2012-06-09 9:00 ` [PATCH -V8 15/16] hugetlb/cgroup: migrate hugetlb cgroup info from oldpage to new page during migration Aneesh Kumar K.V
2012-06-11 9:24 ` Michal Hocko
2012-06-11 10:17 ` Aneesh Kumar K.V
2012-06-12 8:51 ` Kamezawa Hiroyuki
2012-06-12 11:00 ` Aneesh Kumar K.V
2012-06-13 11:15 ` Kamezawa Hiroyuki
2012-06-09 9:00 ` [PATCH -V8 16/16] hugetlb/cgroup: add HugeTLB controller documentation Aneesh Kumar K.V
2012-06-12 8:57 ` Kamezawa Hiroyuki
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