From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Christoph Hellwig <hch@lst.de>
CC: Andrew Morton <akpm@linux-foundation.org>, <linux-mm@kvack.org>,
        <linux-rt-users@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        "Andrey Ryabinin" <aryabinin@virtuozzo.com>,
        Andy Lutomirski <luto@kernel.org>,
        "Joel Fernandes" <joelaf@google.com>,
        Jisheng Zhang <jszhang@marvell.com>,
        "Chris Wilson" <chris@chris-wilson.co.uk>,
        John Dias <joaodias@google.com>,
        "Thomas Gleixner" <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, <x86@kernel.org>
Subject: [PATCH 3/3] x86/ldt: use vfree_atomic() to free ldt entries
Date: Tue, 8 Nov 2016 18:05:45 +0300
Message-ID: <1478617545-8443-3-git-send-email-aryabinin@virtuozzo.com>
In-Reply-To: <1478617545-8443-1-git-send-email-aryabinin@virtuozzo.com>
References: <20161107150947.GA11279@lst.de>
 <1478617545-8443-1-git-send-email-aryabinin@virtuozzo.com>
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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@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jisheng Zhang <jszhang@marvell.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: John Dias <joaodias@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
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