[RFC PATCH 08/13] kernel/fork: Define explicitly which mm_struct to duplicate during fork
From: Till Smejkal <hidden>
Date: 2017-03-13 22:14:10
Also in:
alsa-devel, linux-alpha, linux-api, linux-arch, linux-fsdevel, linux-mips, linux-mm, linux-s390
Subsystem:
exec & binfmt api, elf, memory management - core, scheduler, the rest · Maintainers:
Kees Cook, Andrew Morton, David Hildenbrand, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
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 <redacted> --- 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