From mboxrd@z Thu Jan 1 00:00:00 1970 From: catalin.marinas@arm.com (Catalin Marinas) Date: Fri, 21 Jun 2013 14:52:19 +0100 Subject: BUG: commit "ARM: Remove __ARCH_WANT_INTERRUPTS_ON_CTXSW on pre-ARMv6 CPUs" breaks armv5 with CONFIG_PREEMPT In-Reply-To: <51C42AE0.9070506@pengutronix.de> References: <51C2C0B5.8020802@pengutronix.de> <20130620095705.GA18536@arm.com> <51C2D5EF.3040803@pengutronix.de> <20130620102856.GC18536@arm.com> <20130620111255.GD18536@arm.com> <51C2E917.9000708@pengutronix.de> <51C2EA04.4060701@pengutronix.de> <51C2EBCD.4070206@pengutronix.de> <51C42AE0.9070506@pengutronix.de> Message-ID: <20130621135219.GC4099@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Jun 21, 2013 at 11:28:48AM +0100, Marc Kleine-Budde wrote: > On 06/20/2013 01:47 PM, Marc Kleine-Budde wrote: > > From 306d84d5f0645a86e86d539be0546c4ac758d3d4 Mon Sep 17 00:00:00 2001 > > From: Catalin Marinas > > Date: Thu, 20 Jun 2013 12:12:55 +0100 > > Subject: [PATCH] arm: Fix deferred mm switch on VIVT processors > > > > As of commit b9d4d42ad9 (ARM: Remove __ARCH_WANT_INTERRUPTS_ON_CTXSW on > > pre-ARMv6 CPUs), the mm switching on VIVT processors is done in the > > finish_arch_post_lock_switch() function to avoid whole cache flushing > > with interrupts disabled. The need for deferred mm switch is stored as a > > thread flag (TIF_SWITCH_MM). However, with preemption enabled, we can > > have another thread switch before finish_arch_post_lock_switch(). If the > > new thread has the same mm as the previous 'next' thread, the scheduler > > will not call switch_mm() and the TIF_SWITCH_MM flag won't be set for > > the new thread. > > > > This patch moves the switch pending flag to the mm_context_t structure > > since this is specific to the mm rather than thread. > > > > Signed-off-by: Catalin Marinas > > Reported-by: Marc Kleine-Budde > > [mkl: add check for mm] > > Signed-off-by: Marc Kleine-Budde > > Works on $CUSTOMERS's hardware. > > Tested-by: Marc Kleine-Budde Thanks. > Catalin, do you take care of the patch? Please add stable on Cc. The fix > is needed on kernels >= v3.5. I'll send it to Russell, if possible it should go in for 3.10. I already added CC stable in my copy (3.5+). -- Catalin