On Wed, Oct 05, 2016 at 02:57:04PM -0400, CAI Qian wrote:
> Not sure if this related, and there is always a lockdep regards procfs happened
> below unless masking by other lockdep issues before the cgroup hang. Also, this
> hang is always reproducible.
Sigh... Let's get the /proc/*/auxv out of the way - this should deal with it:
diff --git a/fs/proc/base.c b/fs/proc/base.c
index d588d14..489d2d6 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -400,23 +400,6 @@ static const struct file_operations proc_pid_cmdline_ops = {
.llseek = generic_file_llseek,
};
-static int proc_pid_auxv(struct seq_file *m, struct pid_namespace *ns,
- struct pid *pid, struct task_struct *task)
-{
- struct mm_struct *mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
- if (mm && !IS_ERR(mm)) {
- unsigned int nwords = 0;
- do {
- nwords += 2;
- } while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
- seq_write(m, mm->saved_auxv, nwords * sizeof(mm->saved_auxv[0]));
- mmput(mm);
- return 0;
- } else
- return PTR_ERR(mm);
-}
-
-
#ifdef CONFIG_KALLSYMS
/*
* Provides a wchan file via kallsyms in a proper one-value-per-file format.
@@ -1014,6 +997,30 @@ static const struct file_operations proc_environ_operations = {
.release = mem_release,
};
+static int auxv_open(struct inode *inode, struct file *file)
+{
+ return __mem_open(inode, file, PTRACE_MODE_READ_FSCREDS);
+}
+
+static ssize_t auxv_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct mm_struct *mm = file->private_data;
+ unsigned int nwords = 0;
+ do {
+ nwords += 2;
+ } while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
+ return simple_read_from_buffer(buf, count, ppos, mm->saved_auxv,
+ nwords * sizeof(mm->saved_auxv[0]));
+}
+
+static const struct file_operations proc_auxv_operations = {
+ .open = auxv_open,
+ .read = auxv_read,
+ .llseek = generic_file_llseek,
+ .release = mem_release,
+};
+
static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
loff_t *ppos)
{
@@ -2822,7 +2829,7 @@ static const struct pid_entry tgid_base_stuff[] = {
DIR("net", S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
#endif
REG("environ", S_IRUSR, proc_environ_operations),
- ONE("auxv", S_IRUSR, proc_pid_auxv),
+ REG("auxv", S_IRUSR, proc_auxv_operations),
ONE("status", S_IRUGO, proc_pid_status),
ONE("personality", S_IRUSR, proc_pid_personality),
ONE("limits", S_IRUGO, proc_pid_limits),
@@ -3210,7 +3217,7 @@ static const struct pid_entry tid_base_stuff[] = {
DIR("net", S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
#endif
REG("environ", S_IRUSR, proc_environ_operations),
- ONE("auxv", S_IRUSR, proc_pid_auxv),
+ REG("auxv", S_IRUSR, proc_auxv_operations),
ONE("status", S_IRUGO, proc_pid_status),
ONE("personality", S_IRUSR, proc_pid_personality),
ONE("limits", S_IRUGO, proc_pid_limits),
--
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