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authorLinus Torvalds <torvalds@linux-foundation.org>2018-12-29 11:21:49 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-29 11:21:49 -0800
commit3868772b99e3146d02cf47e739d79022eba1d77c (patch)
treed32c0283496e6955937b618981766b5f0878724f /Documentation/filesystems/proc.txt
parent6f9d71c9c759b1e7d31189a4de228983192c7dc7 (diff)
parent942104a21ce4951420ddf6c6b3179a0627301f7e (diff)
downloadlinux-3868772b99e3146d02cf47e739d79022eba1d77c.tar.bz2
Merge tag 'docs-5.0' of git://git.lwn.net/linux
Pull documentation update from Jonathan Corbet: "A fairly normal cycle for documentation stuff. We have a new document on perf security, more Italian translations, more improvements to the memory-management docs, improvements to the pathname lookup documentation, and the usual array of smaller fixes. As is often the case, there are a few reaches outside of Documentation/ to adjust kerneldoc comments" * tag 'docs-5.0' of git://git.lwn.net/linux: (38 commits) docs: improve pathname-lookup document structure configfs: fix wrong name of struct in documentation docs/mm-api: link slab_common.c to "The Slab Cache" section slab: make kmem_cache_create{_usercopy} description proper kernel-doc doc:process: add links where missing docs/core-api: make mm-api.rst more structured x86, boot: documentation whitespace fixup Documentation: devres: note checking needs when converting doc:it: add some process/* translations doc:it: fixes in process/1.Intro Documentation: convert path-lookup from markdown to resturctured text Documentation/admin-guide: update admin-guide index.rst Documentation/admin-guide: introduce perf-security.rst file scripts/kernel-doc: Fix struct and struct field attribute processing Documentation: dev-tools: Fix typos in index.rst Correct gen_init_cpio tool's documentation Document /proc/pid PID reuse behavior Documentation: update path-lookup.md for parallel lookups Documentation: Use "while" instead of "whilst" dmaengine: Add mailing list address to the documentation ...
Diffstat (limited to 'Documentation/filesystems/proc.txt')
-rw-r--r--Documentation/filesystems/proc.txt13
1 files changed, 12 insertions, 1 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index b24fd9bccc99..66cad5c86171 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -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
..............................................................................
@@ -194,8 +201,10 @@ read the file /proc/PID/status:
CapPrm: 0000000000000000
CapEff: 0000000000000000
CapBnd: ffffffffffffffff
+ CapAmb: 0000000000000000
NoNewPrivs: 0
Seccomp: 0
+ Speculation_Store_Bypass: thread vulnerable
voluntary_ctxt_switches: 0
nonvoluntary_ctxt_switches: 1
@@ -215,7 +224,7 @@ asynchronous manner and the value may not be very precise. To see a precise
snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
It's slow but very precise.
-Table 1-2: Contents of the status files (as of 4.8)
+Table 1-2: Contents of the status files (as of 4.19)
..............................................................................
Field Content
Name filename of the executable
@@ -270,8 +279,10 @@ Table 1-2: Contents of the status files (as of 4.8)
CapPrm bitmap of permitted capabilities
CapEff bitmap of effective capabilities
CapBnd bitmap of capabilities bounding set
+ CapAmb bitmap of ambient capabilities
NoNewPrivs no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...)
Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...)
+ Speculation_Store_Bypass speculative store bypass mitigation status
Cpus_allowed mask of CPUs on which this process may run
Cpus_allowed_list Same as previous, but in "list format"
Mems_allowed mask of memory nodes allowed to this process