From: Richard Weinberger <richard@nod.at>
Date: Sun, 20 Jul 2014 11:16:20 +0000 (+0200)
Subject: um: Fix hung task in fix_range_common()
X-Git-Tag: v4.14-rc1~7202^2~1
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=468f65976a8d065ee1f27782337f4ee85a9151c5;p=platform%2Fkernel%2Flinux-rpi.git

um: Fix hung task in fix_range_common()

If do_ops() fails we have to release current->mm->mmap_sem
otherwise the failing task will never terminate.

Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
---

diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 1fc619e..f1b3eb1 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -12,6 +12,7 @@
 #include <mem_user.h>
 #include <os.h>
 #include <skas.h>
+#include <kern_util.h>
 
 struct host_vm_change {
 	struct host_vm_op {
@@ -286,8 +287,11 @@ void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
 	/* This is not an else because ret is modified above */
 	if (ret) {
 		printk(KERN_ERR "fix_range_common: failed, killing current "
-		       "process\n");
+		       "process: %d\n", task_tgid_vnr(current));
+		/* We are under mmap_sem, release it such that current can terminate */
+		up_write(&current->mm->mmap_sem);
 		force_sig(SIGKILL, current);
+		do_signal();
 	}
 }