On Sep 14, 2011, at 2:43 PM, Anton Blanchard wrote:
Hi Anton, It would really help me a lot if you could review and maybe merge this with my earlier patch that splits this file. <http://patchwork.ozlabs.org/patch/109103/> All it does is split.. I promise. You don't have to take the other stuff.. yet :) -JX > > The icswx code introduced an A-B B-A deadlock: > > CPU0 CPU1 > ---- ---- > lock(&anon_vma->mutex); > lock(&mm->mmap_sem); > lock(&anon_vma->mutex); > lock(&mm->mmap_sem); > > Instead of using the mmap_sem to keep mm_users constant, take the > page table spinlock. > > Signed-off-by: Anton Blanchard <an...@samba.org> > Cc: <sta...@kernel.org> > --- > > diff --git a/arch/powerpc/mm/mmu_context_hash64.c > b/arch/powerpc/mm/mmu_context_hash64.c > index 3bafc3d..4ff587e 100644 > --- a/arch/powerpc/mm/mmu_context_hash64.c > +++ b/arch/powerpc/mm/mmu_context_hash64.c > @@ -136,8 +136,8 @@ int use_cop(unsigned long acop, struct mm_struct *mm) > if (!mm || !acop) > return -EINVAL; > > - /* We need to make sure mm_users doesn't change */ > - down_read(&mm->mmap_sem); > + /* The page_table_lock ensures mm_users won't change under us */ > + spin_lock(&mm->page_table_lock); > spin_lock(mm->context.cop_lockp); > > if (mm->context.cop_pid == COP_PID_NONE) { > @@ -164,7 +164,7 @@ int use_cop(unsigned long acop, struct mm_struct *mm) > > out: > spin_unlock(mm->context.cop_lockp); > - up_read(&mm->mmap_sem); > + spin_unlock(&mm->page_table_lock); > > return ret; > } > @@ -185,8 +185,8 @@ void drop_cop(unsigned long acop, struct mm_struct *mm) > if (WARN_ON_ONCE(!mm)) > return; > > - /* We need to make sure mm_users doesn't change */ > - down_read(&mm->mmap_sem); > + /* The page_table_lock ensures mm_users won't change under us */ > + spin_lock(&mm->page_table_lock); > spin_lock(mm->context.cop_lockp); > > mm->context.acop &= ~acop; > @@ -213,7 +213,7 @@ void drop_cop(unsigned long acop, struct mm_struct *mm) > } > > spin_unlock(mm->context.cop_lockp); > - up_read(&mm->mmap_sem); > + spin_unlock(&mm->page_table_lock); > } > EXPORT_SYMBOL_GPL(drop_cop); > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
