From: "Kani, Toshimitsu" <toshi.kani@hpe.com>
To: "kirill@shutemov.name" <kirill@shutemov.name>
Cc: "tytso@mit.edu" <tytso@mit.edu>,
"mawilcox@microsoft.com" <mawilcox@microsoft.com>,
"david@fromorbit.com" <david@fromorbit.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
"hughd@google.com" <hughd@google.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"adilger.kernel@dilger.ca" <adilger.kernel@dilger.ca>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"jack@suse.cz" <jack@suse.cz>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
"mike.kravetz@oracle.com" <mike.kravetz@oracle.com>
Subject: Re: [PATCH v4 RESEND 0/2] Align mmap address for DAX pmd mappings
Date: Thu, 8 Sep 2016 23:21:46 +0000 [thread overview]
Message-ID: <1473376846.2092.69.camel@hpe.com> (raw)
In-Reply-To: <1473342519.2092.42.camel@hpe.com>
On Thu, 2016-09-08 at 07:48 -0600, Kani, Toshimitsu wrote:
> On Thu, 2016-09-08 at 13:57 +0300, Kirill A. Shutemov wrote:
> >
> > On Mon, Aug 29, 2016 at 10:00:43PM +0000, Kani, Toshimitsu wrote:
:
> > >
> > > Looking further, these shmem_huge handlings only check pre-
> > > conditions. So, we should be able to make shmem_get_unmapped_are
> > > a() as a wrapper, which checks such shmem-specific conitions, and
> > > then call __thp_get_unmapped_area() for the actual work. All
> > > DAX-specific checks are performed in thp_get_unmapped_area() as
> > > well. We can make __thp_get_unmapped_area() as a common
> > > function.
> > >
> > > I'd prefer to make such change as a separate item,
> >
> > Do you have plan to submit such change?
>
> Yes, I will submit the change once I finish testing.
I found a bug in the current code, and need some clarification. The
if-statement below is reverted.
===
diff --git a/mm/shmem.c b/mm/shmem.c
index fd8b2b5..aec5b49 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1980,7 +1980,7 @@ unsigned long shmem_get_unmapped_area(struct file
*file,
return addr;
sb = shm_mnt->mnt_sb;
}
- if (SHMEM_SB(sb)->huge != SHMEM_HUGE_NEVER)
+ if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
return addr;
}
===
Because of this bug, mounting tmpfs with "huge=never" enables huge page
mappings, and "huge=always" or others disables it...
The above simple change will change the default behavior, though. When
"huge=" option is not specified, SHMEM_SB(sb)->huge is set to zero,
which is SHMEM_HUGE_NEVER. Therefore, huge page mappings are enabled
by default because of this bug.
What's the intended default behavior of this feature?
Thanks,
-Toshi
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm
WARNING: multiple messages have this Message-ID (diff)
From: "Kani, Toshimitsu" <toshi.kani@hpe.com>
To: "kirill@shutemov.name" <kirill@shutemov.name>
Cc: "hughd@google.com" <hughd@google.com>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"adilger.kernel@dilger.ca" <adilger.kernel@dilger.ca>,
"mike.kravetz@oracle.com" <mike.kravetz@oracle.com>,
"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
"mawilcox@microsoft.com" <mawilcox@microsoft.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"ross.zwisler@linux.intel.com" <ross.zwisler@linux.intel.com>,
"tytso@mit.edu" <tytso@mit.edu>,
"david@fromorbit.com" <david@fromorbit.com>,
"jack@suse.cz" <jack@suse.cz>
Subject: Re: [PATCH v4 RESEND 0/2] Align mmap address for DAX pmd mappings
Date: Thu, 8 Sep 2016 23:21:46 +0000 [thread overview]
Message-ID: <1473376846.2092.69.camel@hpe.com> (raw)
In-Reply-To: <1473342519.2092.42.camel@hpe.com>
On Thu, 2016-09-08 at 07:48 -0600, Kani, Toshimitsu wrote:
> On Thu, 2016-09-08 at 13:57 +0300, Kirill A. Shutemov wrote:
> >
> > On Mon, Aug 29, 2016 at 10:00:43PM +0000, Kani, Toshimitsu wrote:
:
> > >
> > > Looking further, these shmem_huge handlings only check pre-
> > > conditions. So, we should be able to make shmem_get_unmapped_are
> > > a() as a wrapper, which checks such shmem-specific conitions, and
> > > then call __thp_get_unmapped_area() for the actual work. All
> > > DAX-specific checks are performed in thp_get_unmapped_area() as
> > > well. We can make __thp_get_unmapped_area() as a common
> > > function.
> > >
> > > I'd prefer to make such change as a separate item,
> >
> > Do you have plan to submit such change?
>
> Yes, I will submit the change once I finish testing.
I found a bug in the current code, and need some clarification. The
if-statement below is reverted.
===
diff --git a/mm/shmem.c b/mm/shmem.c
index fd8b2b5..aec5b49 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1980,7 +1980,7 @@ unsigned long shmem_get_unmapped_area(struct file
*file,
return addr;
sb = shm_mnt->mnt_sb;
}
- if (SHMEM_SB(sb)->huge != SHMEM_HUGE_NEVER)
+ if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
return addr;
}
===
Because of this bug, mounting tmpfs with "huge=never" enables huge page
mappings, and "huge=always" or others disables it...
The above simple change will change the default behavior, though. When
"huge=" option is not specified, SHMEM_SB(sb)->huge is set to zero,
which is SHMEM_HUGE_NEVER. Therefore, huge page mappings are enabled
by default because of this bug.
What's the intended default behavior of this feature?
Thanks,
-Toshi
WARNING: multiple messages have this Message-ID (diff)
From: "Kani, Toshimitsu" <toshi.kani@hpe.com>
To: "kirill@shutemov.name" <kirill@shutemov.name>
Cc: "hughd@google.com" <hughd@google.com>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"adilger.kernel@dilger.ca" <adilger.kernel@dilger.ca>,
"mike.kravetz@oracle.com" <mike.kravetz@oracle.com>,
"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
"mawilcox@microsoft.com" <mawilcox@microsoft.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"ross.zwisler@linux.intel.com" <ross.zwisler@linux.intel.com>,
"tytso@mit.edu" <tytso@mit.edu>,
"david@fromorbit.com" <david@fromorbit.com>,
"jack@suse.cz" <jack@suse.cz>
Subject: Re: [PATCH v4 RESEND 0/2] Align mmap address for DAX pmd mappings
Date: Thu, 8 Sep 2016 23:21:46 +0000 [thread overview]
Message-ID: <1473376846.2092.69.camel@hpe.com> (raw)
In-Reply-To: <1473342519.2092.42.camel@hpe.com>
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 2115 bytes --]
On Thu, 2016-09-08 at 07:48 -0600, Kani, Toshimitsu wrote:
> On Thu, 2016-09-08 at 13:57 +0300, Kirill A. Shutemov wrote:
> >
> > On Mon, Aug 29, 2016 at 10:00:43PM +0000, Kani, Toshimitsu wrote:
 :
> > >
> > > Looking further, these shmem_huge handlings only check pre-
> > > conditions.  So, we should be able to make shmem_get_unmapped_are
> > > a() as a wrapper, which checks such shmem-specific conitions, and
> > > then call __thp_get_unmapped_area() for the actual work.  All
> > > DAX-specific checks are performed in thp_get_unmapped_area() as
> > > well.  We can make  __thp_get_unmapped_area() as a common
> > > function.
> > >
> > > I'd prefer to make such change as a separate item,
> >
> > Do you have plan to submit such change?
>
> Yes, I will submit the change once I finish testing.
I found a bug in the current code, and need some clarification. Â The
if-statement below is reverted.
===
diff --git a/mm/shmem.c b/mm/shmem.c
index fd8b2b5..aec5b49 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1980,7 +1980,7 @@ unsigned long shmem_get_unmapped_area(struct file
*file,
                                return addr;
                        sb = shm_mnt->mnt_sb;
                }
-Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â if (SHMEM_SB(sb)->huge != SHMEM_HUGE_NEVER)
+Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
                        return addr;
        }
===
Because of this bug, mounting tmpfs with "huge=never" enables huge page
mappings, and "huge=always" or others disables it...
The above simple change will change the default behavior, though. Â When
"huge=" option is not specified, SHMEM_SB(sb)->huge is set to zero,
which is SHMEM_HUGE_NEVER. Â Therefore, huge page mappings are enabled
by default because of this bug.
What's the intended default behavior of this feature?
Thanks,
-Toshi
N‹§²æìr¸›zǧu©ž²Æ {\b†éì¹»\x1c®&Þ–)îÆi¢žØ^n‡r¶‰šŽŠÝ¢j$½§$¢¸\x05¢¹¨è§~Š'.)îÄÃ,yèm¶ŸÿÃ\f%Š{±šj+ƒðèž×¦j)Z†·Ÿ
next prev parent reply other threads:[~2016-09-08 23:21 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-29 19:11 [PATCH v4 RESEND 0/2] Align mmap address for DAX pmd mappings Toshi Kani
2016-08-29 19:11 ` Toshi Kani
2016-08-29 19:11 ` Toshi Kani
2016-08-29 19:11 ` [PATCH v4 RESEND 1/2] thp, dax: add thp_get_unmapped_area for " Toshi Kani
2016-08-29 19:11 ` Toshi Kani
2016-08-29 19:11 ` Toshi Kani
2016-08-29 19:34 ` Dan Williams
2016-08-29 19:34 ` Dan Williams
2016-08-29 19:34 ` Dan Williams
2016-08-29 20:44 ` Kani, Toshimitsu
2016-08-29 20:44 ` Kani, Toshimitsu
2016-08-29 20:44 ` Kani, Toshimitsu
2016-08-29 20:54 ` Dan Williams
2016-08-29 20:54 ` Dan Williams
2016-08-29 20:54 ` Dan Williams
2016-08-29 19:11 ` [PATCH v4 RESEND 2/2] ext2/4, xfs: call thp_get_unmapped_area() " Toshi Kani
2016-08-29 19:11 ` Toshi Kani
2016-08-29 19:11 ` Toshi Kani
2016-08-29 20:48 ` [PATCH v4 RESEND 0/2] Align mmap address for DAX " Kirill A. Shutemov
2016-08-29 20:48 ` Kirill A. Shutemov
2016-08-29 20:48 ` Kirill A. Shutemov
2016-08-29 21:32 ` Kani, Toshimitsu
2016-08-29 21:32 ` Kani, Toshimitsu
2016-08-29 21:32 ` Kani, Toshimitsu
2016-08-29 22:00 ` Kani, Toshimitsu
2016-08-29 22:00 ` Kani, Toshimitsu
2016-08-29 22:00 ` Kani, Toshimitsu
2016-09-08 10:57 ` Kirill A. Shutemov
2016-09-08 10:57 ` Kirill A. Shutemov
2016-09-08 10:57 ` Kirill A. Shutemov
2016-09-08 13:49 ` Kani, Toshimitsu
2016-09-08 13:49 ` Kani, Toshimitsu
2016-09-08 13:49 ` Kani, Toshimitsu
2016-09-08 23:21 ` Kani, Toshimitsu [this message]
2016-09-08 23:21 ` Kani, Toshimitsu
2016-09-08 23:21 ` Kani, Toshimitsu
2016-09-09 12:36 ` Kirill A. Shutemov
2016-09-09 12:36 ` Kirill A. Shutemov
2016-09-09 12:36 ` Kirill A. Shutemov
2016-09-09 17:21 ` Kani, Toshimitsu
2016-09-09 17:21 ` Kani, Toshimitsu
2016-09-09 17:21 ` Kani, Toshimitsu
2016-09-09 18:37 ` Kirill A. Shutemov
2016-09-09 18:37 ` Kirill A. Shutemov
2016-09-09 18:37 ` Kirill A. Shutemov
2016-09-09 18:37 ` Kirill A. Shutemov
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