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docs/vm: mmu_notifier.txt: convert to ReST format

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Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Mike Rapoport 2018-03-21 21:22:28 +02:00 • committed by Jonathan Corbet
parent 2fcbc41380
commit 16f9f7f924
1 changed files with 57 additions and 51 deletions
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10
Documentation/vm/mmu_notifier.txt
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@ -1,7 +1,10 @@
.. _mmu_notifier:
When do you need to notify inside page table lock ?
===================================================
When clearing a pte/pmd we are given a choice to notify the event through
(notify version of *_clear_flush call mmu_notifier_invalidate_range) under
(notify version of \*_clear_flush call mmu_notifier_invalidate_range) under
the page table lock. But that notification is not necessary in all cases.
For secondary TLB (non CPU TLB) like IOMMU TLB or device TLB (when device use
@ -18,6 +21,7 @@ a page that might now be used by some completely different task.
Case B is more subtle. For correctness it requires the following sequence to
happen:
- take page table lock
- clear page table entry and notify ([pmd/pte]p_huge_clear_flush_notify())
- set page table entry to point to new page
@ -28,9 +32,11 @@ the device.
Consider the following scenario (device use a feature similar to ATS/PASID):
Two address addrA and addrB such that |addrA - addrB| >= PAGE_SIZE we assume
Two address addrA and addrB such that \|addrA - addrB\| >= PAGE_SIZE we assume
they are write protected for COW (other case of B apply too).
::
[Time N] --------------------------------------------------------------------
CPU-thread-0 {try to write to addrA}
CPU-thread-1 {try to write to addrB}