git.stricted.de - GitHub/moto-9609/android_kernel_motorola

author	Anton Ivanov <anton.ivanov@cambridgegreys.com>
	Wed, 5 Dec 2018 12:37:41 +0000 (12:37 +0000)
committer	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
	Tue, 12 Feb 2019 18:46:08 +0000 (19:46 +0100)
commit	e8f13f32f436e3fae2b43a433ec5c677e0e2f5f9
tree	ba86e5331ec972df6442aed95d516d12e5aac188	tree \| snapshot (tar.gz zip)
parent	254c1913cb652d4227fcff87d3518a22e9001062	commit \| diff

um: Avoid marking pages with "changed protection"

[ Upstream commit 8892d8545f2d0342b9c550defbfb165db237044b ]

Changing protection is a very high cost operation in UML
because in addition to an extra syscall it also interrupts
mmap merge sequences generated by the tlb.

While the condition is not particularly common it is worth
avoiding.

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>