| Message ID | 1432298859-2059-1-git-send-email-iago@endocode.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, May 22, 2015 at 02:47:39PM +0200, Iago López Galeiras wrote: > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1145,6 +1145,7 @@ endif # CGROUPS > > config CHECKPOINT_RESTORE > bool "Checkpoint/restore support" if EXPERT > + depends on PROC_CHILDREN > default n > help > Enables additional kernel features in a sake of checkpoint/restore. Maybe better select PROC_CHILDREN here? Also I must admit I don't understand why similar patch from Andy has not been merged earlier? Andy, there was some problem I forgot about? (to be clear, I don't mind enabling it since we use it in criu alot ;) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, May 22, 2015 at 06:37:05PM +0300, Cyrill Gorcunov wrote: > On Fri, May 22, 2015 at 02:47:39PM +0200, Iago López Galeiras wrote: > > --- a/init/Kconfig > > +++ b/init/Kconfig > > @@ -1145,6 +1145,7 @@ endif # CGROUPS > > > > config CHECKPOINT_RESTORE > > bool "Checkpoint/restore support" if EXPERT > > + depends on PROC_CHILDREN > > default n > > help > > Enables additional kernel features in a sake of checkpoint/restore. > > Maybe better select PROC_CHILDREN here? Also I must admit I don't understand > why similar patch from Andy has not been merged earlier? Andy, there was > some problem I forgot about? From the linked thread, it seems that it was just lost... The discussion ended up about task/<tid> and /proc/<pid>... That patch should have been applied. BTW this patch adds the CONFIG guard that was requested by Andrew. There is a v3 coming to make it "select" as suggested. Thanks!
diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig index 2183fcf..d751fcb 100644 --- a/fs/proc/Kconfig +++ b/fs/proc/Kconfig @@ -71,3 +71,7 @@ config PROC_PAGE_MONITOR /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap, /proc/kpagecount, and /proc/kpageflags. Disabling these interfaces will reduce the size of the kernel by approximately 4kb. + +config PROC_CHILDREN + bool "Include /proc/<pid>/task/<tid>/children file" + default n diff --git a/fs/proc/array.c b/fs/proc/array.c index fd02a9e..ddc4b2c 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -569,7 +569,7 @@ int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns, return 0; } -#ifdef CONFIG_CHECKPOINT_RESTORE +#ifdef CONFIG_PROC_CHILDREN static struct pid * get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos) { @@ -692,4 +692,4 @@ const struct file_operations proc_tid_children_operations = { .llseek = seq_lseek, .release = children_seq_release, }; -#endif /* CONFIG_CHECKPOINT_RESTORE */ +#endif /* CONFIG_PROC_CHILDREN */ diff --git a/fs/proc/base.c b/fs/proc/base.c index 093ca14..5477a4a 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2922,7 +2922,7 @@ static const struct pid_entry tid_base_stuff[] = { ONE("stat", S_IRUGO, proc_tid_stat), ONE("statm", S_IRUGO, proc_pid_statm), REG("maps", S_IRUGO, proc_tid_maps_operations), -#ifdef CONFIG_CHECKPOINT_RESTORE +#ifdef CONFIG_PROC_CHILDREN REG("children", S_IRUGO, proc_tid_children_operations), #endif #ifdef CONFIG_NUMA diff --git a/init/Kconfig b/init/Kconfig index dc24dec..daa7941 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1145,6 +1145,7 @@ endif # CGROUPS config CHECKPOINT_RESTORE bool "Checkpoint/restore support" if EXPERT + depends on PROC_CHILDREN default n help Enables additional kernel features in a sake of checkpoint/restore.
commit 818411616baf ("fs, proc: introduce /proc/<pid>/task/<tid>/children entry") introduced the children entry for checkpoint restore and the file is only available on kernels configured with CONFIG_EXPERT and CONFIG_CHECKPOINT_RESTORE. This is available in most distributions (Fedora, Debian, Ubuntu, CoreOS) because they usually enable CONFIG_EXPERT and CONFIG_CHECKPOINT_RESTORE. But Arch does not enable CONFIG_EXPERT or CONFIG_CHECKPOINT_RESTORE. However, the children proc file is useful outside of checkpoint restore. I would like to use it in rkt. The rkt process exec() another program it does not control, and that other program will fork()+exec() a child process. I would like to find the pid of the child process from an external tool without iterating in /proc over all processes to find which one has a parent pid equal to rkt. This commit introduces CONFIG_PROC_CHILDREN and makes CONFIG_CHECKPOINT_RESTORE depend on it. This allows enabling /proc/<pid>/task/<tid>/children without needing to enable CONFIG_CHECKPOINT_RESTORE and CONFIG_EXPERT. Alban tested that /proc/<pid>/task/<tid>/children is present when the kernel is configured with CONFIG_PROC_CHILDREN=y but without CONFIG_CHECKPOINT_RESTORE Signed-off-by: Iago López Galeiras <iago@endocode.com> Cc: Alban Crequy <alban@endocode.com> Tested-by: Alban Crequy <alban@endocode.com> --- fs/proc/Kconfig | 4 ++++ fs/proc/array.c | 4 ++-- fs/proc/base.c | 2 +- init/Kconfig | 1 + 4 files changed, 8 insertions(+), 3 deletions(-)