The patch titled
Subject: pid: restore the old behaviour of the ns_last_pid sysctl
has been added to the -mm tree. Its filename is
pid-replace-pid-bitmap-implementation-with-idr-api-v6-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/pid-replace-pid-bitmap-implementation-with-idr-api-v6-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/pid-replace-pid-bitmap-implementation-with-idr-api-v6-fix.patch
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------------------------------------------------------
From: Andrei Vagin <avagin@xxxxxxxxxx>
Subject: pid: restore the old behaviour of the ns_last_pid sysctl
CRIU uses ns_last_pid to fork a process with a specified pid. For
example, if we need to create a process with the pid of 10000, we write
9999 into /proc/sys/kernel/ns_last_pid
$ echo 9999 > /proc/sys/kernel/ns_last_pid; sh -c 'echo $$'
10000
This behaviour has been broken and now if we write 9999 to ns_last_pid,
a process will get the pid 9999. This patch restores the old behaviour.
v2: make code a bit more readable // Oleg
Link: http://lkml.kernel.org/r/20171106183144.16368-1-avagin@xxxxxxxxxx
fixes: ("pid: replace pid bitmap implementation with IDR API")
Signed-off-by: Andrei Vagin <avagin@xxxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Gargi Sharma <gs051095@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/pid_namespace.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff -puN kernel/pid_namespace.c~pid-replace-pid-bitmap-implementation-with-idr-api-v6-fix kernel/pid_namespace.c
--- a/kernel/pid_namespace.c~pid-replace-pid-bitmap-implementation-with-idr-api-v6-fix
+++ a/kernel/pid_namespace.c
@@ -287,6 +287,7 @@ static int pid_ns_ctl_handler(struct ctl
{
struct pid_namespace *pid_ns = task_active_pid_ns(current);
struct ctl_table tmp = *table;
+ int ret, next;
if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
return -EPERM;
@@ -297,8 +298,14 @@ static int pid_ns_ctl_handler(struct ctl
* it should synchronize its usage with external means.
*/
- tmp.data = &pid_ns->idr.idr_next;
- return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
+ next = idr_get_cursor(&pid_ns->idr) - 1;
+
+ tmp.data = &next;
+ ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
+ if (!ret && write)
+ idr_set_cursor(&pid_ns->idr, next + 1);
+
+ return ret;
}
extern int pid_max;
_
Patches currently in -mm which might be from avagin@xxxxxxxxxx are
pid-replace-pid-bitmap-implementation-with-idr-api-v6-fix.patch
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