From 2d566537dd2c69bd6898ef5d95ecccdfbab97eef Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Mon, 2 May 2016 16:21:50 +0530 Subject: powerpc/mm/subpage: Initialise user psize correctly As part of the radix support we switched Book3s64 to use a value of ~0 for MMU_NO_CONTEXT. That is because id 0 is special on radix. However that broke the logic in init_new_context(). The code there needs to differentiate between a newly allocated context and one inherited via fork. Previously it worked because a newly allocated context has an id of zero (because it was just memset() to zero), which used to match MMU_NO_CONTEXT, and therefore slice_mm_new_context() did the right thing. Instead check against a context.id value of zero instead of using slice_mm_new_context(). Without this patch we never call slice_set_user_psize(), and end up with a slice psize value of zero and we always end up using 4K HPTE. Fixes: 1a472c9dba6b ("powerpc/mm/radix: Add tlbflush routines") Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c index b5288b4..227b2a6 100644 --- a/arch/powerpc/mm/mmu_context_book3s64.c +++ b/arch/powerpc/mm/mmu_context_book3s64.c @@ -85,8 +85,17 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm) /* The old code would re-promote on fork, we don't do that * when using slices as it could cause problem promoting slices * that have been forced down to 4K + * + * For book3s we have MMU_NO_CONTEXT set to be ~0. Hence check + * explicitly against context.id == 0. This ensures that we + * properly initialize context slice details for newly allocated + * mm's (which will have id == 0) and don't alter context slice + * inherited via fork (which will have id != 0). + * + * We should not be calling init_new_context() on init_mm. Hence a + * check against 0 is ok. */ - if (slice_mm_new_context(mm)) + if (mm->context.id == 0) slice_set_user_psize(mm, mmu_virtual_psize); subpage_prot_init_new_context(mm); } -- cgit v0.10.2