Will Deacon 0106d456c4 arm64: mm: always take dirty state from new pte in ptep_set_access_flags ... Commit 66dbd6e61a ("arm64: Implement ptep_set_access_flags() for hardware AF/DBM") ensured that pte flags are updated atomically in the face of potential concurrent, hardware-assisted updates. However, Alex reports that: | This patch breaks swapping for me. | In the broken case, you'll see either systemd cpu time spike (because | it's stuck in a page fault loop) or the system hang (because the | application owning the screen is stuck in a page fault loop). It turns out that this is because the 'dirty' argument to ptep_set_access_flags is always 0 for read faults, and so we can't use it to set PTE_RDONLY. The failing sequence is: 1. We put down a PTE_WRITE | PTE_DIRTY | PTE_AF pte 2. Memory pressure -> pte_mkold(pte) -> clear PTE_AF 3. A read faults due to the missing access flag 4. ptep_set_access_flags is called with dirty = 0, due to the read fault 5. pte is then made PTE_WRITE | PTE_DIRTY | PTE_AF | PTE_RDONLY (!) 6. A write faults, but pte_write is true so we get stuck The solution is to check the new page table entry (as would be done by the generic, non-atomic definition of ptep_set_access_flags that just calls set_pte_at) to establish the dirty state. Cc: <stable@vger.kernel.org> # 4.3+ Fixes: 66dbd6e61a ("arm64: Implement ptep_set_access_flags() for hardware AF/DBM") Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reported-by: Alexander Graf <agraf@suse.de> Tested-by: Alexander Graf <agraf@suse.de> Signed-off-by: Will Deacon <will.deacon@arm.com>		2016-06-08 10:23:44 +01:00
..
boot	ARM: SoC: late DT updates for v4.7	2016-05-24 15:46:06 -07:00
configs	Merge git://www.linux-watchdog.org/linux-watchdog	2016-05-25 10:19:17 -07:00
crypto	Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6	2016-03-17 11:22:54 -07:00
include	arm64: move {PAGE,CONT}_SHIFT into Kconfig	2016-06-03 10:57:18 +01:00
kernel	arm64: report CPU number in bad_mode	2016-06-03 10:16:20 +01:00
kvm	arm64: KVM: vgic-v3: Relax synchronization when SRE==1	2016-05-31 16:12:17 +02:00
lib	arm64 updates for 4.6:	2016-03-17 20:03:47 -07:00
mm	arm64: mm: always take dirty state from new pte in ptep_set_access_flags	2016-06-08 10:23:44 +01:00
net	bpf: arm64: remove callee-save registers use for tmp registers	2016-05-17 14:03:33 -04:00
xen	xen/arm: introduce HYPERVISOR_platform_op on arm and arm64	2015-12-21 14:40:56 +00:00
Kconfig	Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2016-06-03 16:12:35 -07:00
Kconfig.debug	arm64: enable CONFIG_SET_MODULE_RONX by default	2016-05-31 14:23:29 +01:00
Kconfig.platforms	ARM: SoC 64-bit changes for v4.7	2016-05-18 12:43:08 -07:00
Makefile	arm64: fix alignment when RANDOMIZE_TEXT_OFFSET is enabled	2016-06-03 10:57:18 +01:00