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Unshare mount namespace in bootchart's thread

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When bootchart is enabled its thread shares the mount namespace context
with the main thread. This prevents the main thread to switch the mount
namespace later with setns().

So, unshare() the mount namespace of the bootchart thread.

Bug: 229983560
Test: rebooted with bootcharting on/off
    enter_default_mount_ns should succeeded.
Change-Id: Idac0d0efcb4f7f7d8a7cbcebf8fa2fa29f104c35
This commit is contained in:
Jooyung Han 2022-04-22 12:05:09 +09:00
parent d438ea723b
commit 7f8721b992
1 changed files with 14 additions and 0 deletions
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14
init/bootchart.cpp
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@ -140,6 +140,20 @@ static void log_processes(FILE* log) {
static void bootchart_thread_main() {
LOG(INFO) << "Bootcharting started";
// Unshare the mount namespace of this thread so that the init process itself can switch
// the mount namespace later while this thread is still running.
// Otherwise, setns() call invoked as part of `enter_default_mount_ns` fails with EINVAL.
//
// Note that after unshare()'ing the mount namespace from the main thread, this thread won't
// receive mount/unmount events from the other mount namespace unless the events are happening
// from under a sharable mount.
//
// The bootchart thread is safe to unshare the mount namespace because it only reads from /proc
// and write to /data which are not private mounts.
if (unshare(CLONE_NEWNS) == -1) {
PLOG(ERROR) << "Cannot create mount namespace";
return;
}
// Open log files.
auto stat_log = fopen_unique("/data/bootchart/proc_stat.log", "we");
if (!stat_log) return;