Thread (17 messages) 17 messages, 3 authors, 2016-11-08
STALE3511d

[PATCH 3/3] x86/ldt: use vfree_atomic() to free ldt entries

From: Andrey Ryabinin <hidden>
Date: 2016-11-08 15:22:57
Also in: linux-mm, lkml
Subsystem: the rest, x86 architecture (32-bit and 64-bit) · Maintainers: Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen

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 <redacted>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Joel Fernandes <redacted>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jisheng Zhang <redacted>
Cc: Chris Wilson <redacted>
Cc: John Dias <redacted>
Cc: Thomas Gleixner <redacted>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
---
 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);
-- 
2.7.3

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