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Alex Xu (Hello71) 46c4c9d1be pipe: increase minimum default pipe size to 2 pages
This program always prints 4096 and hangs before the patch, and always
prints 8192 and exits successfully after:

  int main()
  {
      int pipefd[2];
      for (int i = 0; i < 1025; i++)
          if (pipe(pipefd) == -1)
              return 1;
      size_t bufsz = fcntl(pipefd[1], F_GETPIPE_SZ);
      printf("%zd\n", bufsz);
      char *buf = calloc(bufsz, 1);
      write(pipefd[1], buf, bufsz);
      read(pipefd[0], buf, bufsz-1);
      write(pipefd[1], buf, 1);
  }

Note that you may need to increase your RLIMIT_NOFILE before running the
program.

Fixes: 759c01142a ("pipe: limit the per-user amount of pages allocated in pipes")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/lkml/1628086770.5rn8p04n6j.none@localhost/
Link: https://lore.kernel.org/lkml/1628127094.lxxn016tj7.none@localhost/
Signed-off-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-08-05 10:30:47 -07:00
arch powerpc fixes for 5.14 #4 2021-08-01 12:18:44 -07:00
block block-5.14-2021-07-30 2021-07-30 11:08:12 -07:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-07-09 11:00:44 -07:00
Documentation ARM: 2021-07-29 09:42:09 -07:00
drivers SCSI fixes on 20210804 2021-08-04 12:41:30 -07:00
fs pipe: increase minimum default pipe size to 2 pages 2021-08-05 10:30:47 -07:00
include Networking fixes for 5.14-rc4, including fixes from bpf, can, WiFi (mac80211) 2021-07-30 16:01:36 -07:00
init Revert "mm/slub: use stackdepot to save stack trace in objects" 2021-07-17 13:27:00 -07:00
ipc Merge branch 'akpm' (patches from Andrew) 2021-07-02 12:08:10 -07:00
kernel Networking fixes for 5.14-rc4, including fixes from bpf, can, WiFi (mac80211) 2021-07-30 16:01:36 -07:00
lib lib/test_string.c: move string selftest in the Runtime Testing menu 2021-07-30 10:14:39 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/memcg: fix NULL pointer dereference in memcg_slab_free_hook() 2021-07-30 10:14:39 -07:00
net Networking fixes for 5.14-rc4, including fixes from bpf, can, WiFi (mac80211) 2021-07-30 16:01:36 -07:00
samples Networking fixes for 5.14-rc2, including fixes from bpf and netfilter. 2021-07-14 09:24:32 -07:00
scripts Kbuild fixes for v5.14 2021-07-18 11:10:30 -07:00
security asm-generic/unaligned: Unify asm/unaligned.h around struct helper 2021-07-02 12:43:40 -07:00
sound sound fixes for 5.14-rc3 2021-07-23 09:58:23 -07:00
tools perf tools fixes for v5.14: 2nd batch 2021-08-01 12:25:30 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: add missing compat KVM_CLEAR_DIRTY_LOG 2021-07-27 16:59:01 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap m68k updates for v5.14 2021-06-28 14:01:03 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 5.14-rc4, including fixes from bpf, can, WiFi (mac80211) 2021-07-30 16:01:36 -07:00
Makefile Linux 5.14-rc4 2021-08-01 17:04:17 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.