[PATCH 06/10] x86/ldt: use vfree_atomic() to free ldt entries

From: Christoph Hellwig
Date: Fri Nov 18 2016 - 08:05:43 EST


From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>

vfree() is going to use sleeping lock. free_ldt_struct()
may be called with disabled preemption, therefore we must
use vfree_atomic() here.

E.g. call trace:
vfree()
free_ldt_struct()
destroy_context_ldt()
__mmdrop()
finish_task_switch()
schedule_tail()
ret_from_fork()

Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
---
arch/x86/kernel/ldt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index 6707039..4d12cdf 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -93,7 +93,7 @@ static void free_ldt_struct(struct ldt_struct *ldt)

paravirt_free_ldt(ldt->entries, ldt->size);
if (ldt->size * LDT_ENTRY_SIZE > PAGE_SIZE)
- vfree(ldt->entries);
+ vfree_atomic(ldt->entries);
else
free_page((unsigned long)ldt->entries);
kfree(ldt);
--
2.1.4