From: Andrea Arcangeli <aarcange@redhat.com>
To: Chen Gang <xili_gchen_5257@hotmail.com>
Cc: Richard Weinberger <richard.weinberger@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
"riel@redhat.com" <riel@redhat.com>,
Michal Hocko <mhocko@suse.cz>,
"oleg@redhat.com" <oleg@redhat.com>,
"asha.levin@oracle.com" <asha.levin@oracle.com>,
"pfeiner@google.com" <pfeiner@google.com>,
"vishnu.ps@samsung.com" <vishnu.ps@samsung.com>,
Linux Memory <linux-mm@kvack.org>,
kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm/mmap.c: Remove redundant vma looping
Date: Sun, 4 Oct 2015 19:26:45 +0200 [thread overview]
Message-ID: <20151004172645.GO19466@redhat.com> (raw)
In-Reply-To: <BLU436-SMTP233624CAE8A4C054B5DFFF8B9490@phx.gbl>
Hello Chen,
On Sun, Oct 04, 2015 at 12:55:29PM +0800, Chen Gang wrote:
> Theoretically, the lock and unlock need to be symmetric, if we have to
> lock f_mapping all firstly, then lock all anon_vma, probably, we also
> need to unlock anon_vma all, then unlock all f_mapping.
They don't need to be symmetric because the unlocking order doesn't
matter. To avoid lock inversion deadlocks it is enough to enforce the
lock order.
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WARNING: multiple messages have this Message-ID (diff)
From: Andrea Arcangeli <aarcange@redhat.com>
To: Chen Gang <xili_gchen_5257@hotmail.com>
Cc: Richard Weinberger <richard.weinberger@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
"riel@redhat.com" <riel@redhat.com>,
Michal Hocko <mhocko@suse.cz>,
"oleg@redhat.com" <oleg@redhat.com>,
"asha.levin@oracle.com" <asha.levin@oracle.com>,
"pfeiner@google.com" <pfeiner@google.com>,
"vishnu.ps@samsung.com" <vishnu.ps@samsung.com>,
Linux Memory <linux-mm@kvack.org>,
kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm/mmap.c: Remove redundant vma looping
Date: Sun, 4 Oct 2015 19:26:45 +0200 [thread overview]
Message-ID: <20151004172645.GO19466@redhat.com> (raw)
In-Reply-To: <BLU436-SMTP233624CAE8A4C054B5DFFF8B9490@phx.gbl>
Hello Chen,
On Sun, Oct 04, 2015 at 12:55:29PM +0800, Chen Gang wrote:
> Theoretically, the lock and unlock need to be symmetric, if we have to
> lock f_mapping all firstly, then lock all anon_vma, probably, we also
> need to unlock anon_vma all, then unlock all f_mapping.
They don't need to be symmetric because the unlocking order doesn't
matter. To avoid lock inversion deadlocks it is enough to enforce the
lock order.
next prev parent reply other threads:[~2015-10-04 17:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-03 19:38 [PATCH] mm/mmap.c: Remove redundant vma looping Chen Gang
2015-10-03 20:09 ` Richard Weinberger
2015-10-03 20:09 ` Richard Weinberger
2015-10-04 4:55 ` Chen Gang
2015-10-04 4:55 ` Chen Gang
2015-10-04 17:26 ` Andrea Arcangeli [this message]
2015-10-04 17:26 ` Andrea Arcangeli
2015-10-05 12:23 ` Chen Gang
2015-10-05 12:23 ` Chen Gang
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