linux-kernel - [PATCH] x86/ldt: Initialize the context lock for init

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Message-ID: <20190701173354.2pe62hhliok2afea@linutronix.de>
Date:   Mon, 1 Jul 2019 19:33:54 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Nadav Amit <namit@...are.com>
Subject: [PATCH] x86/ldt: Initialize the context lock for init_mm

The mutex mm->context->lock for init_mm is not initialized for init_mm.
This wasn't a problem because it remained unused. This changed however
since commit
	4fc19708b165c ("x86/alternatives: Initialize temporary mm for patching")

Initialize the mutex for init_mm.

Fixes: 4fc19708b165c ("x86/alternatives: Initialize temporary mm for patching")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---

The rwsem `ldt_usr_sem' is also not initialized for init_mm. No idea if
we want this.

 arch/x86/include/asm/mmu.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
index 5ff3e8af2c205..e78c7db878018 100644
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -59,6 +59,7 @@ typedef struct {
 #define INIT_MM_CONTEXT(mm)						\
 	.context = {							\
 		.ctx_id = 1,						\
+		.lock = __MUTEX_INITIALIZER(mm.context.lock),		\
 	}
 
 void leave_mm(int cpu);
-- 
2.20.1