On Tue, 6 Mar 2018 15:48:26 -0500 Pavel Tatashin <[email protected]> wrote:
> On Tue, Mar 6, 2018 at 3:36 PM, Andrew Morton <[email protected]> > wrote: > > > On Tue, 6 Mar 2018 14:20:22 -0500 Pavel Tatashin < > > [email protected]> wrote: > > > > > spin_lock(&deferred_zone_grow_lock); > > > - static_branch_disable(&deferred_pages); > > > + deferred_zone_grow = false; > > > spin_unlock(&deferred_zone_grow_lock); > > > + static_branch_disable(&deferred_pages); > > > > > > /* There will be num_node_state(N_MEMORY) threads */ > > > atomic_set(&pgdat_init_n_undone, num_node_state(N_MEMORY)); > > > > Kinda ugly, but I can see the logic behind the decisions. > > > > Can we instead turn deferred_zone_grow_lock into a mutex? (top-posting repaired. Please don't top-post). > [CCed everyone] > > Hi Andrew, > > I afraid we cannot change this spinlock to mutex > because deferred_grow_zone() might be called from an interrupt context if > interrupt thread needs to allocate memory. > OK. But if deferred_grow_zone() can be called from interrupt then page_alloc_init_late() should be using spin_lock_irq(), shouldn't it? I'm surprised that lockdep didn't detect that. --- a/mm/page_alloc.c~mm-initialize-pages-on-demand-during-boot-fix-4-fix +++ a/mm/page_alloc.c @@ -1689,9 +1689,9 @@ void __init page_alloc_init_late(void) * context. Since, spin_lock() disables preemption, we must use an * extra boolean deferred_zone_grow. */ - spin_lock(&deferred_zone_grow_lock); + spin_lock_irq(&deferred_zone_grow_lock); deferred_zone_grow = false; - spin_unlock(&deferred_zone_grow_lock); + spin_unlock_irq(&deferred_zone_grow_lock); static_branch_disable(&deferred_pages); /* There will be num_node_state(N_MEMORY) threads */ _
