4.14.87-rt50-rc1 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
[ Upstream commit 45c6ff4811878e5c1c2ae31303cd95cdc6ae2ab4 ]
Commit "x86/mm/pat: Disable preemption around __flush_tlb_all()" added a
warning if __flush_tlb_all() is invoked in preemptible context. On !RT
the warning does not trigger because a spin lock is acquired which
disables preemption. On RT the spin lock does not disable preemption and
so the warning is seen.
Disable preemption to avoid the warning __flush_tlb_all().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
arch/x86/mm/pageattr.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 835620ab435f..57a04ef6fe47 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -661,12 +661,18 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
pgprot_t ref_prot;
spin_lock(&pgd_lock);
+ /*
+ * Keep preemption disabled after __flush_tlb_all() which expects not be
+ * preempted during the flush of the local TLB.
+ */
+ preempt_disable();
/*
* Check for races, another CPU might have split this page
* up for us already:
*/
tmp = _lookup_address_cpa(cpa, address, &level);
if (tmp != kpte) {
+ preempt_enable();
spin_unlock(&pgd_lock);
return 1;
}
@@ -696,6 +702,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
break;
default:
+ preempt_enable();
spin_unlock(&pgd_lock);
return 1;
}
@@ -743,6 +750,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
* going on.
*/
__flush_tlb_all();
+ preempt_enable();
spin_unlock(&pgd_lock);
return 0;
--
2.19.2
