Lines Matching +full:4 +full:kb +full:- +full:page
1 .. SPDX-License-Identifier: GPL-2.0
24 1.1 Process-Specific Subdirectories
36 3 Per-Process Parameters
37 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer
39 3.2 /proc/<pid>/oom_score - Display current oom-killer score
40 3.3 /proc/<pid>/io - Display the IO accounting fields
41 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
42 3.5 /proc/<pid>/mountinfo - Information about mounts
44 3.7 /proc/<pid>/task/<tid>/children - Information about task children
45 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
46 3.9 /proc/<pid>/map_files - Information about memory mapped files
47 3.10 /proc/<pid>/timerslack_ns - Task timerslack value
48 3.11 /proc/<pid>/patch_state - Livepatch patch operation state
49 3.12 /proc/<pid>/arch_status - Task architecture specific information
50 3.13 /proc/<pid>/fd - List of symlinks to open files
52 4 Configuring procfs
61 ------------------------
69 we know, it is the first 'all-in-one' document about the /proc file system. It
72 It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
91 mailing list at linux-kernel@vger.kernel.org and/or try to reach me at
95 ---------------
105 ---------------
112 ------------------------------------------------------------------------------
118 First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
121 1.1 Process-Specific Subdirectories
122 -----------------------------------
128 subdirectory has the entries listed in Table 1-1.
138 .. table:: Table 1-1: Process specific entries in /proc
143 clear_refs Clears page referenced bits shown in smaps output
157 symbol the task is blocked in - or "0" if not blocked.
158 pagemap Page table
183 VmPeak: 5004 kB
184 VmSize: 5004 kB
185 VmLck: 0 kB
186 VmHWM: 476 kB
187 VmRSS: 476 kB
188 RssAnon: 352 kB
189 RssFile: 120 kB
190 RssShmem: 4 kB
191 VmData: 156 kB
192 VmStk: 88 kB
193 VmExe: 68 kB
194 VmLib: 1412 kB
195 VmPTE: 20 kb
196 VmSwap: 0 kB
197 HugetlbPages: 0 kB
222 file /proc/PID/status. It fields are described in table 1-2.
225 memory usage. Its seven fields are explained in Table 1-3. The stat file
227 explained in Table 1-4.
233 snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
236 .. table:: Table 1-2: Contents of the status fields (as of 4.19)
277 VmPTE size of page table entries
310 .. table:: Table 1-3: Contents of the statm fields (as of 2.6.8-rc3)
328 .. table:: Table 1-4: Contents of the stat fields (as of 2.6.30-rc7)
397 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test
398 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
399 0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
400 a7cb1000-a7cb2000 ---p 00000000 00:00 0
401 a7cb2000-a7eb2000 rw-p 00000000 00:00 0
402 a7eb2000-a7eb3000 ---p 00000000 00:00 0
403 a7eb3000-a7ed5000 rw-p 00000000 00:00 0
404 a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
405 a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
406 a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
407 a800b000-a800e000 rw-p 00000000 00:00 0
408 a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
409 a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
410 a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
411 a8024000-a8027000 rw-p 00000000 00:00 0
412 a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
413 a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
414 a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
415 aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
416 ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
450 08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
452 Size: 1084 kB
453 KernelPageSize: 4 kB
454 MMUPageSize: 4 kB
455 Rss: 892 kB
456 Pss: 374 kB
457 Pss_Dirty: 0 kB
458 Shared_Clean: 892 kB
459 Shared_Dirty: 0 kB
460 Private_Clean: 0 kB
461 Private_Dirty: 0 kB
462 Referenced: 892 kB
463 Anonymous: 0 kB
464 KSM: 0 kB
465 LazyFree: 0 kB
466 AnonHugePages: 0 kB
467 ShmemPmdMapped: 0 kB
468 Shared_Hugetlb: 0 kB
469 Private_Hugetlb: 0 kB
470 Swap: 0 kB
471 SwapPss: 0 kB
472 KernelPageSize: 4 kB
473 MMUPageSize: 4 kB
474 Locked: 0 kB
480 (size); the size of each page allocated when backing a VMA (KernelPageSize),
481 which is usually the same as the size in the page table entries; the page size
488 in memory, where each page is divided by the number of processes sharing it.
494 Note that even a page which is part of a MAP_SHARED mapping, but has only
503 and a page is modified, the file page is replaced by a private anonymous copy.
505 "KSM" reports how many of the pages are KSM pages. Note that KSM-placed zeropages
520 hugetlbfs page which is *not* counted in "RSS" or "PSS" field for historical
523 "Swap" shows how much would-be-anonymous memory is also used, but out on swap.
526 replaced by copy-on-write) part of the underlying shmem object out on swap.
528 does not take into account swapped out page of underlying shmem objects.
532 pages as well as the THP is PMD mappable or not - 1 if true, 0 otherwise.
560 sf synchronous page fault
566 hg huge page advise flag
567 nh no huge page advise flag
569 bt arm64 BTI guarded page
572 uw userfaultfd wr-protect tracking
573 ss shadow stack page
578 be vanished or the reverse -- new added. Interpretation of their meaning
601 - Pss_Anon
602 - Pss_File
603 - Pss_Shmem
613 soft-dirty bit on pte (see Documentation/admin-guide/mm/soft-dirty.rst
627 To clear the soft-dirty bit::
629 > echo 4 > /proc/PID/clear_refs
639 using /proc/kpageflags and number of times a page is mapped using
641 Documentation/admin-guide/mm/pagemap.rst.
650 00400000 default file=/usr/local/bin/app mapped=1 active=0 N3=1 kernelpagesize_kB=4
651 00600000 default file=/usr/local/bin/app anon=1 dirty=1 N3=1 kernelpagesize_kB=4
652 3206000000 default file=/lib64/ld-2.12.so mapped=26 mapmax=6 N0=24 N3=2 kernelpagesize_kB=4
653 320621f000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
654 3206220000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
655 3206221000 default anon=1 dirty=1 N3=1 kernelpagesize_kB=4
656 …3206800000 default file=/lib64/libc-2.12.so mapped=59 mapmax=21 active=55 N0=41 N3=18 kernelpagesi…
657 320698b000 default file=/lib64/libc-2.12.so
658 3206b8a000 default file=/lib64/libc-2.12.so anon=2 dirty=2 N3=2 kernelpagesize_kB=4
659 3206b8e000 default file=/lib64/libc-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
660 3206b8f000 default anon=3 dirty=3 active=1 N3=3 kernelpagesize_kB=4
661 7f4dc10a2000 default anon=3 dirty=3 N3=3 kernelpagesize_kB=4
662 7f4dc10b4000 default anon=2 dirty=2 active=1 N3=2 kernelpagesize_kB=4
664 7fff335f0000 default stack anon=3 dirty=3 N3=3 kernelpagesize_kB=4
665 7fff3369d000 default mapped=1 mapmax=35 active=0 N3=1 kernelpagesize_kB=4
671 "policy" reports the NUMA memory policy set for the mapping (see Documentation/admin-guide/mm/numa_…
673 "mapping details" summarizes mapping data such as mapping type, page usage counters,
674 node locality page counters (N0 == node0, N1 == node1, ...) and the kernel page
675 size, in KB, that is backing the mapping up.
678 ---------------
682 /proc and are listed in Table 1-5. Not all of these will be present in your
686 .. table:: Table 1-5: Kernel info in /proc
726 pagetypeinfo Additional page allocator information (see text) (2.5)
728 pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
750 0: 8728810 XT-PIC timer
751 1: 895 XT-PIC keyboard
752 2: 0 XT-PIC cascade
753 3: 531695 XT-PIC aha152x
754 4: 2014133 XT-PIC serial
755 5: 44401 XT-PIC pcnet_cs
756 8: 2 XT-PIC rtc
757 11: 8 XT-PIC i82365
758 12: 182918 XT-PIC PS/2 Mouse
759 13: 1 XT-PIC fpu
760 14: 1232265 XT-PIC ide0
761 15: 7 XT-PIC ide1
770 0: 1243498 1214548 IO-APIC-edge timer
771 1: 8949 8958 IO-APIC-edge keyboard
772 2: 0 0 XT-PIC cascade
773 5: 11286 10161 IO-APIC-edge soundblaster
774 8: 1 0 IO-APIC-edge rtc
775 9: 27422 27407 IO-APIC-edge 3c503
776 12: 113645 113873 IO-APIC-edge PS/2 Mouse
777 13: 0 0 XT-PIC fpu
778 14: 22491 24012 IO-APIC-edge ide0
779 15: 2183 2415 IO-APIC-edge ide1
780 17: 30564 30414 IO-APIC-level eth0
781 18: 177 164 IO-APIC-level bttv
791 ERR is incremented in the case of errors in the IO-APIC bus (the bus that
793 the IO-APIC automatically retry the transmission, so it should not be a big
794 problem, but you should read the SMP-FAQ.
837 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
859 1024-1031
861 The default_smp_affinity mask applies to all non-active IRQs, which are the
863 /proc/irq/[0-9]* directory.
872 The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
875 best choice for almost everyone. [Note this applies only to those IO-APIC's
885 Linux uses slab pools for memory management above page level in version 2.2.
893 Node 0, zone DMA 0 4 5 4 4 3 ...
904 ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
911 Page block order: 9
914 …Free pages count per migrate type at order 0 1 2 3 4 5 6 …
931 migrate types into the same contiguous regions of memory called page blocks.
932 A page block is typically the size of the default hugepage size, e.g. 2MB on
933 X86-64. By keeping pages grouped based on their ability to move, the kernel
934 can reclaim pages within a page block to satisfy a high-order allocation.
936 The pagetypinfo begins with information on the size of a page block. It
938 by migrate-type and finishes with details on how many page blocks of each
967 MemTotal: 32858820 kB
968 MemFree: 21001236 kB
969 MemAvailable: 27214312 kB
970 Buffers: 581092 kB
971 Cached: 5587612 kB
972 SwapCached: 0 kB
973 Active: 3237152 kB
974 Inactive: 7586256 kB
975 Active(anon): 94064 kB
976 Inactive(anon): 4570616 kB
977 Active(file): 3143088 kB
978 Inactive(file): 3015640 kB
979 Unevictable: 0 kB
980 Mlocked: 0 kB
981 SwapTotal: 0 kB
982 SwapFree: 0 kB
983 Zswap: 1904 kB
984 Zswapped: 7792 kB
985 Dirty: 12 kB
986 Writeback: 0 kB
987 AnonPages: 4654780 kB
988 Mapped: 266244 kB
989 Shmem: 9976 kB
990 KReclaimable: 517708 kB
991 Slab: 660044 kB
992 SReclaimable: 517708 kB
993 SUnreclaim: 142336 kB
994 KernelStack: 11168 kB
995 PageTables: 20540 kB
996 SecPageTables: 0 kB
997 NFS_Unstable: 0 kB
998 Bounce: 0 kB
999 WritebackTmp: 0 kB
1000 CommitLimit: 16429408 kB
1001 Committed_AS: 7715148 kB
1002 VmallocTotal: 34359738367 kB
1003 VmallocUsed: 40444 kB
1004 VmallocChunk: 0 kB
1005 Percpu: 29312 kB
1006 EarlyMemtestBad: 0 kB
1007 HardwareCorrupted: 0 kB
1008 AnonHugePages: 4149248 kB
1009 ShmemHugePages: 0 kB
1010 ShmemPmdMapped: 0 kB
1011 FileHugePages: 0 kB
1012 FilePmdMapped: 0 kB
1013 CmaTotal: 0 kB
1014 CmaFree: 0 kB
1019 Hugepagesize: 2048 kB
1020 Hugetlb: 0 kB
1021 DirectMap4k: 401152 kB
1022 DirectMap2M: 10008576 kB
1023 DirectMap1G: 24117248 kB
1036 page cache to function well, and that not all reclaimable
1043 In-memory cache for files read from the disk (the
1087 Non-file backed pages mapped into userspace page tables
1097 in-kernel data structures cache
1105 Memory consumed by userspace page tables
1107 Memory consumed by secondary page tables, this currently
1125 CommitLimit = ([total RAM pages] - [total huge TLB pages]) *
1133 in mm/overcommit-accounting.
1158 The amount of RAM/memory in kB, that was identified as corrupted
1160 be displayed at all. Size is never rounded down to 0 kB.
1161 That means if 0 kB is reported, you can safely assume
1165 The amount of RAM/memory in KB, the kernel identifies as
1168 Non-file backed huge pages mapped into userspace page tables
1175 Memory used for filesystem data (page cache) allocated
1178 Page cache mapped into userspace with huge pages
1184 See Documentation/admin-guide/mm/hugetlbpage.rst.
1186 Breakdown of page table sizes used in the kernel's
1212 0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
1214 0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
1216 0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
1218 0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
1220 0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
1221 0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
1223 0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
1225 0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
1226 /0x130 [x_tables] pages=4 vmalloc N0=4
1227 0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
1229 0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
1230 pages=4 vmalloc N1=4
1231 0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
1233 0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
1257 --------------------------------
1259 The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
1261 support this. Table 1-9 lists the files and their meaning.
1264 .. table:: Table 1-8: IPv6 info in /proc/net
1280 .. table:: Table 1-9: Network info in /proc/net
1302 softnet_stat Per-CPU incoming packets queues statistics of online CPUs
1318 Inter-|Receive |[...
1337 -------------
1347 Type: Direct-Access ANSI SCSI revision: 03
1349 Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
1350 Type: CD-ROM ANSI SCSI revision: 02
1357 AHA-2940 SCSI adapter::
1361 Adaptec AIC7xxx driver version: 5.1.19/3.2.4
1367 SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
1374 Allocated 15, HW 16, Page 255
1400 ---------------------------------------
1406 These directories contain the four files shown in Table 1-10.
1409 .. table:: Table 1-10: Files in /proc/parport
1414 autoprobe Any IEEE-1284 device ID information that has been acquired.
1425 -------------------------
1429 this directory, as shown in Table 1-11.
1432 .. table:: Table 1-11: Files in /proc/tty
1446 pty_slave /dev/pts 136 0-255 pty:slave
1447 pty_master /dev/ptm 128 0-255 pty:master
1448 pty_slave /dev/ttyp 3 0-255 pty:slave
1449 pty_master /dev/pty 2 0-255 pty:master
1450 serial /dev/cua 5 64-67 serial:callout
1451 serial /dev/ttyS 4 64-67 serial
1452 /dev/tty0 /dev/tty0 4 0 system:vtmaster
1456 unknown /dev/tty 4 1-63 console
1460 -------------------------------------------------
1485 - user: normal processes executing in user mode
1486 - nice: niced processes executing in user mode
1487 - system: processes executing in kernel mode
1488 - idle: twiddling thumbs
1489 - iowait: In a word, iowait stands for waiting for I/O to complete. But there
1495 2. In a multi-core CPU, the task waiting for I/O to complete is not running
1501 - irq: servicing interrupts
1502 - softirq: servicing softirqs
1503 - steal: involuntary wait
1504 - guest: running a normal guest
1505 - guest_nice: running a niced guest
1535 -------------------------------
1540 /proc/fs/ext4/sda9 or /proc/fs/ext4/dm-0). The files in each per-device
1541 directory are shown in Table 1-12, below.
1543 .. table:: Table 1-12: Files in /proc/fs/ext4/<devname>
1551 -------------------
1558 tty0 -WU (ECp) 4:7
1559 ttyS0 -W- (Ep) 4:64
1563 +--------------------+-------------------------------------------------------+
1569 +--------------------+-------------------------------------------------------+
1576 +--------------------+-------------------------------------------------------+
1579 +--------------------+-------------------------------------------------------+
1582 -------
1595 ---------------
1601 ------------------------------------------------------------------------------
1625 Please see: Documentation/admin-guide/sysctl/ directory for descriptions of
1629 -------
1638 Chapter 3: Per-process Parameters
1641 3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
1642 --------------------------------------------------------------------------------
1664 is used to determine which task to kill. Acceptable values range from -1000
1667 task or completely disabling it. The lowest possible value, -1000, is
1675 50% more memory. A value of -500, on the other hand, would be roughly
1680 be used to tune the badness score. Its acceptable values range from -16
1681 (OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
1690 3.2 /proc/<pid>/oom_score - Display current oom-killer score
1691 -------------------------------------------------------------
1693 This file can be used to check the current score used by the oom-killer for
1695 process should be killed in an out-of-memory situation.
1701 3.3 /proc/<pid>/io - Display the IO accounting fields
1702 -------------------------------------------------------
1768 accurate for block-backed filesystems. <please add status regarding NFS and
1777 the storage layer. This is done at page-dirtying time.
1796 At its current implementation state, this is a bit racy on 32-bit machines:
1798 of those 64-bit counters, process A could see an intermediate result.
1804 3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
1805 ---------------------------------------------------------------
1809 Conversely, sometimes we want to save file-backed memory segments into a core
1819 - (bit 0) anonymous private memory
1820 - (bit 1) anonymous shared memory
1821 - (bit 2) file-backed private memory
1822 - (bit 3) file-backed shared memory
1823 - (bit 4) ELF header pages in file-backed private memory areas (it is
1825 - (bit 5) hugetlb private memory
1826 - (bit 6) hugetlb shared memory
1827 - (bit 7) DAX private memory
1828 - (bit 8) DAX shared memory
1833 Note that bits 0-4 don't affect hugetlb or DAX memory. hugetlb memory is
1834 only affected by bit 5-6, and DAX is only affected by bits 7-8.
1851 3.5 /proc/<pid>/mountinfo - Information about mounts
1852 --------------------------------------------------------
1856 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
1857 (1)(2)(3) (4) (5) (6) (n…m) (m+1)(m+2) (m+3) (m+4)
1862 (4) root: root of the mount within the filesystem
1869 (m+4) super options: per super block options
1892 --------------------------------------------------------
1900 3.7 /proc/<pid>/task/<tid>/children - Information about task children
1901 -------------------------------------------------------------------------
1906 Note the "first level" here -- if a child has its own children they will
1907 not be listed here; one needs to read /proc/<children-pid>/task/<tid>/children
1917 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
1918 ---------------------------------------------------------------
1920 files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'.
1951 eventfd-count: 5a
1953 where 'eventfd-count' is hex value of a counter.
1996 …inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_han…
2005 fields 'fhandle-bytes', 'fhandle-type' and 'f_handle', all in hex
2019 fanotify flags:10 event-flags:0
2021 …fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type…
2023 where fanotify 'flags' and 'event-flags' are values used in fanotify_init
2069 exp_name: system-heap
2074 3.9 /proc/<pid>/map_files - Information about memory mapped files
2075 ---------------------------------------------------------------------
2079 | lr-------- 1 root root 64 Jan 27 11:24 333c600000-333c620000 -> /usr/lib64/ld-2.18.so
2080 | lr-------- 1 root root 64 Jan 27 11:24 333c81f000-333c820000 -> /usr/lib64/ld-2.18.so
2081 | lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so
2083 | lr-------- 1 root root 64 Jan 27 11:24 35d0421000-35d0422000 -> /usr/lib64/libselinux.so.1
2084 | lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls
2087 vm_area_struct::vm_start-vm_area_struct::vm_end.
2096 3.10 /proc/<pid>/timerslack_ns - Task timerslack value
2097 ---------------------------------------------------------
2107 Valid values are from 0 - ULLONG_MAX
2112 3.11 /proc/<pid>/patch_state - Livepatch patch operation state
2113 -----------------------------------------------------------------
2117 A value of '-1' indicates that no patch is in transition.
2129 3.12 /proc/<pid>/arch_status - task architecture specific status
2130 -------------------------------------------------------------------
2170 A special value of '-1' indicates that no AVX512 usage was recorded, thus
2174 3.13 /proc/<pid>/fd - List of symlinks to open files
2175 -------------------------------------------------------
2179 lr-x------ 1 root root 64 Sep 20 17:53 0 -> /dev/null
2180 l-wx------ 1 root root 64 Sep 20 17:53 1 -> /dev/null
2181 lrwx------ 1 root root 64 Sep 20 17:53 10 -> 'socket:[12539]'
2182 lrwx------ 1 root root 64 Sep 20 17:53 11 -> 'socket:[12540]'
2183 lrwx------ 1 root root 64 Sep 20 17:53 12 -> 'socket:[12542]'
2187 -------------------------------------------------------
2190 Chapter 4: Configuring procfs
2194 ---------------------
2204 hidepid=off or hidepid=0 means classic mode - everybody may access all
2218 by "kill -0 $PID"), but it hides process' uid and gid, which may be learned by
2224 hidepid=ptraceable or hidepid=4 means that procfs should only contain
2247 # strace -e mount mount -o hidepid=1 -t proc proc /tmp/proc
2258 # mount -o remount,hidepid=1 -t proc proc /tmp/proc
2271 # mount -o hidepid=invisible -t proc proc /proc
2272 # mount -o hidepid=noaccess -t proc proc /tmp/proc