From: Andrew Morton <akpm@linux-foundation.org>
To: jglisse@redhat.com
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
"Matthew Wilcox" <mawilcox@microsoft.com>,
"Ross Zwisler" <zwisler@kernel.org>, "Jan Kara" <jack@suse.cz>,
"Dan Williams" <dan.j.williams@intel.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Michal Hocko" <mhocko@kernel.org>,
"Christian Koenig" <christian.koenig@amd.com>,
"Felix Kuehling" <felix.kuehling@amd.com>,
"Ralph Campbell" <rcampbell@nvidia.com>,
"John Hubbard" <jhubbard@nvidia.com>,
kvm@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-fsdevel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 3/3] mm/mmu_notifier: contextual information for event triggering invalidation
Date: Tue, 4 Dec 2018 15:21:37 -0800 [thread overview]
Message-ID: <20181204152137.5e6791987739fd64ce7ea421@linux-foundation.org> (raw)
In-Reply-To: <20181203201817.10759-4-jglisse@redhat.com>
On Mon, 3 Dec 2018 15:18:17 -0500 jglisse@redhat.com wrote:
> CPU page table update can happens for many reasons, not only as a result
> of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also
> as a result of kernel activities (memory compression, reclaim, migration,
> ...).
>
> Users of mmu notifier API track changes to the CPU page table and take
> specific action for them. While current API only provide range of virtual
> address affected by the change, not why the changes is happening.
>
> This patchset adds event information so that users of mmu notifier can
> differentiate among broad category:
> - UNMAP: munmap() or mremap()
> - CLEAR: page table is cleared (migration, compaction, reclaim, ...)
> - PROTECTION_VMA: change in access protections for the range
> - PROTECTION_PAGE: change in access protections for page in the range
> - SOFT_DIRTY: soft dirtyness tracking
>
> Being able to identify munmap() and mremap() from other reasons why the
> page table is cleared is important to allow user of mmu notifier to
> update their own internal tracking structure accordingly (on munmap or
> mremap it is not longer needed to track range of virtual address as it
> becomes invalid).
>
> ...
>
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -519,6 +519,7 @@ bool __oom_reap_task_mm(struct mm_struct *mm)
> struct mmu_notifier_range range;
> struct mmu_gather tlb;
>
> + range.event = MMU_NOTIFY_CLEAR;
> range.start = vma->vm_start;
> range.end = vma->vm_end;
> range.mm = mm;
mmu_notifier_range and MMU_NOTIFY_CLEAR aren't defined if
CONFIG_MMU_NOTIFIER=n.
I'll try a temporary bodge:
+++ a/include/linux/mmu_notifier.h
@@ -10,8 +10,6 @@
struct mmu_notifier;
struct mmu_notifier_ops;
-#ifdef CONFIG_MMU_NOTIFIER
-
/*
* The mmu notifier_mm structure is allocated and installed in
* mm->mmu_notifier_mm inside the mm_take_all_locks() protected
@@ -32,6 +30,8 @@ struct mmu_notifier_range {
bool blockable;
};
+#ifdef CONFIG_MMU_NOTIFIER
+
struct mmu_notifier_ops {
/*
* Called either by mmu_notifier_unregister or when the mm is
But this new code should vanish altogether if CONFIG_MMU_NOTIFIER=n,
please. Or at least, we shouldn't be unnecessarily initializing .mm
and .event. Please take a look at debloating this code.
next prev parent reply other threads:[~2018-12-04 23:21 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-03 20:18 [PATCH 0/3] mmu notifier contextual informations jglisse
2018-12-03 20:18 ` [PATCH 1/3] mm/mmu_notifier: use structure for invalidate_range_start/end callback jglisse
2018-12-03 20:18 ` [PATCH 2/3] mm/mmu_notifier: use structure for invalidate_range_start/end calls jglisse
2018-12-04 0:09 ` Jerome Glisse
2018-12-05 11:04 ` Jan Kara
2018-12-05 15:53 ` Jerome Glisse
2018-12-05 16:28 ` Jan Kara
2018-12-06 20:31 ` kbuild test robot
2018-12-06 20:35 ` kbuild test robot
2018-12-03 20:18 ` [PATCH 3/3] mm/mmu_notifier: contextual information for event triggering invalidation jglisse
2018-12-04 8:17 ` Mike Rapoport
2018-12-04 14:48 ` Jerome Glisse
2018-12-04 23:21 ` Andrew Morton [this message]
2018-12-06 20:53 ` kbuild test robot
2018-12-06 21:19 ` kbuild test robot
2018-12-06 21:51 ` Jerome Glisse
2018-12-04 7:35 ` [PATCH 0/3] mmu notifier contextual informations Koenig, Christian
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