Document /proc/pid PID reuse behavior (c969eb83) · Commits · 戴 / test

State explicitly that holding a /proc/pid file descriptor open does not reserve the PID. Also note that in the event of PID reuse, these open file descriptors refer to the old, now-dead process, and not the new one that happens to be named the same numeric PID. Signed-off-by:

Daniel Colascione <dancol@google.com> Acked-by:

Michal Hocko <mhocko@suse.com> Reviewed-by:

Mike Rapoport <rppt@linux.ibm.com> Signed-off-by:

Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/proc.txt

+7 −0

Original line number	Diff line number	Diff line
		@@ -125,6 +125,13 @@ process running on the system, which is named after the process ID (PID).
		The link self points to the process reading the file system. Each process
		subdirectory has the entries listed in Table 1-1.

		Note that an open a file descriptor to /proc/<pid> or to any of its
		contained files or subdirectories does not prevent <pid> being reused
		for some other process in the event that <pid> exits. Operations on
		open /proc/<pid> file descriptors corresponding to dead processes
		never act on any new process that the kernel may, through chance, have
		also assigned the process ID <pid>. Instead, operations on these FDs
		usually fail with ESRCH.

		Table 1-1: Process specific entries in /proc
		..............................................................................

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