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um: Avoid marking pages with "changed protection"
authorAnton Ivanov <anton.ivanov@cambridgegreys.com>
Wed, 5 Dec 2018 12:37:41 +0000 (12:37 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 12 Feb 2019 18:44:58 +0000 (19:44 +0100)
commit5eb9de20b9cc44e58ae83ec37a8791814d37a1ce
tree2257965da6287208d4a42d5295803ccb42f6aae8tree | snapshot
parent5c61a608d8e186415e4665b9087faeb8255abdb9commit | 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>
arch/um/include/asm/pgtable.h diff | blob | history
wrapfs-5.3.y