linux-kernel - Re: [PATCH -V4 02/10] hugetlbfs: don't use ERR_PTR with VM

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Message-ID: <87vclpyn3e.fsf@skywalker.in.ibm.com>
Date:	Wed, 28 Mar 2012 17:05:49 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	linux-mm@...ck.org, mgorman@...e.de,
	kamezawa.hiroyu@...fujitsu.com, dhillf@...il.com,
	aarcange@...hat.com, akpm@...ux-foundation.org, hannes@...xchg.org,
	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org
Subject: Re: [PATCH -V4 02/10] hugetlbfs: don't use ERR_PTR with VM_FAULT* values

Michal Hocko <mhocko@...e.cz> writes:

> On Fri 16-03-12 23:09:22, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
>> 
>> Using VM_FAULT_* codes with ERR_PTR will require us to make sure
>> VM_FAULT_* values will not exceed MAX_ERRNO value.
>> 
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
>> ---
>>  mm/hugetlb.c |   18 +++++++++++++-----
>>  1 files changed, 13 insertions(+), 5 deletions(-)
>> 
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>> index d623e71..3782da8 100644
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
> [...]
>> @@ -1047,7 +1047,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
>>  		page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
>>  		if (!page) {
>>  			hugetlb_put_quota(inode->i_mapping, chg);
>> -			return ERR_PTR(-VM_FAULT_SIGBUS);
>> +			return ERR_PTR(-ENOSPC);
>
> Hmm, so one error code abuse replaced by another?
> I know that ENOMEM would revert 4a6018f7 which would be unfortunate but
> ENOSPC doesn't feel right as well.
>

File systems do map ENOSPC to SIGBUS. block_page_mkwrite_return() does
that.

-aneesh

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