linux-toradex.git/kernel/pid.c, branch v5.1-rc1

Fix failure path in alloc_pid()

2018-12-28T20:42:30+00:00

The failure path removes the allocated PIDs from the wrong namespace.
This could lead to us inadvertently reusing PIDs in the leaf namespace
and leaking PIDs in parent namespaces.

Fixes: 95846ecf9dac ("pid: replace pid bitmap implementation with IDR API")
Cc: 
Signed-off-by: Matthew Wilcox 
Acked-by: "Eric W. Biederman" 
Reviewed-by: Oleg Nesterov 
Signed-off-by: Linus Torvalds

mm: remove include/linux/bootmem.h

2018-10-31T15:54:16+00:00

Move remaining definitions and declarations from include/linux/bootmem.h
into include/linux/memblock.h and remove the redundant header.

The includes were replaced with the semantic patch below and then
semi-automated removal of duplicated '#include 

@@
@@
- #include 
+ #include 

[sfr@canb.auug.org.au: dma-direct: fix up for the removal of linux/bootmem.h]
  Link: http://lkml.kernel.org/r/20181002185342.133d1680@canb.auug.org.au
[sfr@canb.auug.org.au: powerpc: fix up for removal of linux/bootmem.h]
  Link: http://lkml.kernel.org/r/20181005161406.73ef8727@canb.auug.org.au
[sfr@canb.auug.org.au: x86/kaslr, ACPI/NUMA: fix for linux/bootmem.h removal]
  Link: http://lkml.kernel.org/r/20181008190341.5e396491@canb.auug.org.au
Link: http://lkml.kernel.org/r/1536927045-23536-30-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport 
Signed-off-by: Stephen Rothwell 
Acked-by: Michal Hocko 
Cc: Catalin Marinas 
Cc: Chris Zankel 
Cc: "David S. Miller" 
Cc: Geert Uytterhoeven 
Cc: Greentime Hu 
Cc: Greg Kroah-Hartman 
Cc: Guan Xuetao 
Cc: Ingo Molnar 
Cc: "James E.J. Bottomley" 
Cc: Jonas Bonn 
Cc: Jonathan Corbet 
Cc: Ley Foon Tan 
Cc: Mark Salter 
Cc: Martin Schwidefsky 
Cc: Matt Turner 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Palmer Dabbelt 
Cc: Paul Burton 
Cc: Richard Kuo 
Cc: Richard Weinberger 
Cc: Rich Felker 
Cc: Russell King 
Cc: Serge Semin 
Cc: Thomas Gleixner 
Cc: Tony Luck 
Cc: Vineet Gupta 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fork: report pid exhaustion correctly

2018-09-20T20:01:11+00:00

Make the clone and fork syscalls return EAGAIN when the limit on the
number of pids /proc/sys/kernel/pid_max is exceeded.

Currently, when the pid_max limit is exceeded, the kernel will return
ENOSPC from the fork and clone syscalls.  This is contrary to the
documented behaviour, which explicitly calls out the pid_max case as one
where EAGAIN should be returned.  It also leads to really confusing error
messages in userspace programs which will complain about a lack of disk
space when they fail to create processes/threads for this reason.

This error is being returned because alloc_pid() uses the idr api to find
a new pid; when there are none available, idr_alloc_cyclic() returns
-ENOSPC, and this is being propagated back to userspace.

This behaviour has been broken before, and was explicitly fixed in
commit 35f71bc0a09a ("fork: report pid reservation failure properly"),
so I think -EAGAIN is definitely the right thing to return in this case.
The current behaviour change dates from commit 95846ecf9dac ("pid:
replace pid bitmap implementation with IDR AIP") and was I believe
unintentional.

This patch has no impact on the case where allocating a pid fails because
the child reaper for the namespace is dead; that case will still return
-ENOMEM.

Link: http://lkml.kernel.org/r/20180903111016.46461-1-ktsanaktsidis@zendesk.com
Fixes: 95846ecf9dac ("pid: replace pid bitmap implementation with IDR AIP")
Signed-off-by: KJ Tsanaktsidis 
Reviewed-by: Andrew Morton 
Acked-by: Michal Hocko 
Cc: Gargi Sharma 
Cc: Rik van Riel 
Cc: Oleg Nesterov 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

pid: Implement PIDTYPE_TGID

2018-07-21T15:43:12+00:00

Everywhere except in the pid array we distinguish between a tasks pid and
a tasks tgid (thread group id).  Even in the enumeration we want that
distinction sometimes so we have added __PIDTYPE_TGID.  With leader_pid
we almost have an implementation of PIDTYPE_TGID in struct signal_struct.

Add PIDTYPE_TGID as a first class member of the pid_type enumeration and
into the pids array.  Then remove the __PIDTYPE_TGID special case and the
leader_pid in signal_struct.

The net size increase is just an extra pointer added to struct pid and
an extra pair of pointers of an hlist_node added to task_struct.

The effect on code maintenance is the removal of a number of special
cases today and the potential to remove many more special cases as
PIDTYPE_TGID gets used to it's fullest.  The long term potential
is allowing zombie thread group leaders to exit, which will remove
a lot more special cases in the code.

Signed-off-by: "Eric W. Biederman"

pids: Move the pgrp and session pid pointers from task_struct to signal_struct

2018-07-21T15:43:12+00:00

To access these fields the code always has to go to group leader so
going to signal struct is no loss and is actually a fundamental simplification.

This saves a little bit of memory by only allocating the pid pointer array
once instead of once for every thread, and even better this removes a
few potential races caused by the fact that group_leader can be changed
by de_thread, while signal_struct can not.

Signed-off-by: "Eric W. Biederman"

pids: Compute task_tgid using signal->leader_pid

2018-07-21T15:43:12+00:00

The cost is the the same and this removes the need
to worry about complications that come from de_thread
and group_leader changing.

__task_pid_nr_ns has been updated to take advantage of this change.

Signed-off-by: "Eric W. Biederman"

xarray: add the xa_lock to the radix_tree_root

2018-04-11T17:28:39+00:00

This results in no change in structure size on 64-bit machines as it
fits in the padding between the gfp_t and the void *.  32-bit machines
will grow the structure from 8 to 12 bytes.  Almost all radix trees are
protected with (at least) a spinlock, so as they are converted from
radix trees to xarrays, the data structures will shrink again.

Initialising the spinlock requires a name for the benefit of lockdep, so
RADIX_TREE_INIT() now needs to know the name of the radix tree it's
initialising, and so do IDR_INIT() and IDA_INIT().

Also add the xa_lock() and xa_unlock() family of wrappers to make it
easier to use the lock.  If we could rely on -fplan9-extensions in the
compiler, we could avoid all of this syntactic sugar, but that wasn't
added until gcc 4.6.

Link: http://lkml.kernel.org/r/20180313132639.17387-8-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Reviewed-by: Jeff Layton 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Ryusuke Konishi 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

pids: introduce find_get_task_by_vpid() helper

2018-02-07T02:32:46+00:00

There are several functions that do find_task_by_vpid() followed by
get_task_struct().  We can use a helper function instead.

Link: http://lkml.kernel.org/r/1509602027-11337-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport 
Acked-by: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'init_task-20180117' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

2018-01-29T17:08:34+00:00

Pull init_task initializer cleanups from David Howells:
 "It doesn't seem useful to have the init_task in a header file rather
  than in a normal source file. We could consolidate init_task handling
  instead and expand out various macros.

  Here's a series of patches that consolidate init_task handling:

   (1) Make THREAD_SIZE available to vmlinux.lds for cris, hexagon and
       openrisc.

   (2) Alter the INIT_TASK_DATA linker script macro to set
       init_thread_union and init_stack rather than defining these in C.

       Insert init_task and init_thread_into into the init_stack area in
       the linker script as appropriate to the configuration, with
       different section markers so that they end up correctly ordered.

       We can then get merge ia64's init_task.c into the main one.

       We then have a bunch of single-use INIT_*() macros that seem only
       to be macros because they used to be used per-arch. We can then
       expand these in place of the user and get rid of a few lines and
       a lot of backslashes.

   (3) Expand INIT_TASK() in place.

   (4) Expand in place various small INIT_*() macros that are defined
       conditionally. Expand them and surround them by #if[n]def/#endif
       in the .c file as it takes fewer lines.

   (5) Expand INIT_SIGNALS() and INIT_SIGHAND() in place.

   (6) Expand INIT_STRUCT_PID in place.

  These macros can then be discarded"

* tag 'init_task-20180117' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  Expand INIT_STRUCT_PID and remove
  Expand the INIT_SIGNALS and INIT_SIGHAND macros and remove
  Expand various INIT_* macros and remove
  Expand INIT_TASK() in init/init_task.c and remove
  Construct init thread stack in the linker script rather than by union
  openrisc: Make THREAD_SIZE available to vmlinux.lds
  hexagon: Make THREAD_SIZE available to vmlinux.lds
  cris: Make THREAD_SIZE available to vmlinux.lds

Expand INIT_STRUCT_PID and remove

2018-01-17T11:30:16+00:00

Expand INIT_STRUCT_PID in the single place that uses it and then remove it.
There doesn't seem any point in the macro.

Signed-off-by: David Howells 
Tested-by: Tony Luck 
Tested-by: Will Deacon  (arm64)
Tested-by: Palmer Dabbelt 
Acked-by: Thomas Gleixner