From mboxrd@z Thu Jan  1 00:00:00 1970
From: Till Smejkal <till.smejkal@googlemail.com>
Subject: [RFC PATCH 08/13] kernel/fork: Define explicitly which mm_struct to duplicate during fork
Date: Mon, 13 Mar 2017 15:14:10 -0700
Message-ID: <20170313221415.9375-9-till.smejkal@gmail.com>
References: <20170313221415.9375-1-till.smejkal@gmail.com>
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To: Richard Henderson <rth@twiddle.net>, Ivan Kokshaysky <ink@jurassic.park.msu.ru>, Matt Turner <mattst88@gmail.com>, Vineet Gupta <vgupta@synopsys.com>, Russell King <linux@armlinux.org.uk>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Steven Miao <realmz6@gmail.com>, Richard Kuo <rkuo@codeaurora.org>, Tony Luck <tony.luck@intel.com>, Fenghua Yu <fenghua.yu@intel.com>, James Hogan <james.hogan@imgtec.com>, Ralf Baechle <ralf@linux-mips.org>, "James E.J. Bottomley" <jejb@parisc-linux.org>, Helge Deller <deller@gmx.de>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Yoshinori Sato <ysato@users.sourceforge.jp>, Rich Felker <dalias@libc.org>, "David S. Miller" <davem@dave>
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List-Id: linux-api@vger.kernel.org

The dup_mm-function used during 'do_fork' to duplicate the current task's
mm_struct for the newly forked task always implicitly uses current->mm for
this purpose. However, during copy_mm it was already decided which
mm_struct to copy/duplicate. So pass this mm_struct to dup_mm instead of
again deciding which mm_struct to use.

Signed-off-by: Till Smejkal <till.smejkal@gmail.com>
---
 kernel/fork.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 9209f6d5d7c0..d3087d870855 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1158,9 +1158,10 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
  * Allocate a new mm structure and copy contents from the
  * mm structure of the passed in task structure.
  */
-static struct mm_struct *dup_mm(struct task_struct *tsk)
+static struct mm_struct *dup_mm(struct task_struct *tsk,
+				struct mm_struct *oldmm)
 {
-	struct mm_struct *mm, *oldmm = current->mm;
+	struct mm_struct *mm;
 	int err;
 
 	mm = allocate_mm();
@@ -1226,7 +1227,7 @@ static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
 	}
 
 	retval = -ENOMEM;
-	mm = dup_mm(tsk);
+	mm = dup_mm(tsk, oldmm);
 	if (!mm)
 		goto fail_nomem;
 
-- 
2.12.0

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