linux-kernel - [PATCH v3 3/9] Uprobe: Move mmput() into free_map

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Date:   Tue, 17 Apr 2018 10:02:38 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
To:     mhiramat@...nel.org, oleg@...hat.com, peterz@...radead.org,
        srikar@...ux.vnet.ibm.com, rostedt@...dmis.org
Cc:     acme@...nel.org, ananth@...ux.vnet.ibm.com,
        akpm@...ux-foundation.org, alexander.shishkin@...ux.intel.com,
        alexis.berlemont@...il.com, corbet@....net,
        dan.j.williams@...el.com, jolsa@...hat.com, kan.liang@...el.com,
        kjlx@...pleofstupid.com, kstewart@...uxfoundation.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, milian.wolff@...b.com, mingo@...hat.com,
        namhyung@...nel.org, naveen.n.rao@...ux.vnet.ibm.com,
        pc@...ibm.com, tglx@...utronix.de, yao.jin@...ux.intel.com,
        fengguang.wu@...el.com, jglisse@...hat.com,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: [PATCH v3 3/9] Uprobe: Move mmput() into free_map_info()

From: Oleg Nesterov <oleg@...hat.com>

build_map_info() has a side effect like one need to perform
mmput() when done with the mm. Add mmput() in free_map_info()
so that user does not have to call it explicitly.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
---
 kernel/events/uprobes.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 535fd39..1d439c7 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -704,6 +704,7 @@ struct map_info {
 static inline struct map_info *free_map_info(struct map_info *info)
 {
 	struct map_info *next = info->next;
+	mmput(info->mm);
 	kfree(info);
 	return next;
 }
@@ -773,8 +774,11 @@ static inline struct map_info *free_map_info(struct map_info *info)
 
 	goto again;
  out:
-	while (prev)
-		prev = free_map_info(prev);
+	while (prev) {
+		info = prev;
+		prev = prev->next;
+		kfree(info);
+	}
 	return curr;
 }
 
@@ -824,7 +828,6 @@ static inline struct map_info *free_map_info(struct map_info *info)
  unlock:
 		up_write(&mm->mmap_sem);
  free:
-		mmput(mm);
 		info = free_map_info(info);
 	}
  out:
-- 
1.8.3.1