user/sven/linux.git/kernel/pid.c, branch v4.19.228

Fix failure path in alloc_pid()

2019-01-13T08:51:06Z

commit 1a80dade010c7a7f4885a4c4c2a7ac22cc7b34df upstream. 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 Signed-off-by: Greg Kroah-Hartman

fork: report pid exhaustion correctly

2018-09-20T20:01:11Z

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

2018-07-21T15:43:12Z

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

2018-07-21T15:43:12Z

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

2018-07-21T15:43:12Z

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

2018-04-11T17:28:39Z

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

2018-02-07T02:32:46Z

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

2018-01-29T17:08:34Z

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

2018-01-17T11:30:16Z

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

pid: Handle failure to allocate the first pid in a pid namespace

2017-12-24T03:00:09Z

With the replacement of the pid bitmap and hashtable with an idr in alloc_pid started occassionally failing when allocating the first pid in a pid namespace. Things were not completely reset resulting in the first allocated pid getting the number 2 (not 1). Which further resulted in ns->proc_mnt not getting set and eventually causing an oops in proc_flush_task. Oops: 0000 [#1] SMP CPU: 2 PID: 6743 Comm: trinity-c117 Not tainted 4.15.0-rc4-think+ #2 RIP: 0010:proc_flush_task+0x8e/0x1b0 RSP: 0018:ffffc9000bbffc40 EFLAGS: 00010286 RAX: 0000000000000001 RBX: 0000000000000001 RCX: 00000000fffffffb RDX: 0000000000000000 RSI: ffffc9000bbffc50 RDI: 0000000000000000 RBP: ffffc9000bbffc63 R08: 0000000000000000 R09: 0000000000000002 R10: ffffc9000bbffb70 R11: ffffc9000bbffc64 R12: 0000000000000003 R13: 0000000000000000 R14: 0000000000000003 R15: ffff8804c10d7840 FS: 00007f7cb8965700(0000) GS:ffff88050a200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000003e21ae003 CR4: 00000000001606e0 DR0: 00007fb1d6c22000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: ? release_task+0xaf/0x680 release_task+0xd2/0x680 ? wait_consider_task+0xb82/0xce0 wait_consider_task+0xbe9/0xce0 ? do_wait+0xe1/0x330 do_wait+0x151/0x330 kernel_wait4+0x8d/0x150 ? task_stopped_code+0x50/0x50 SYSC_wait4+0x95/0xa0 ? rcu_read_lock_sched_held+0x6c/0x80 ? syscall_trace_enter+0x2d7/0x340 ? do_syscall_64+0x60/0x210 do_syscall_64+0x60/0x210 entry_SYSCALL64_slow_path+0x25/0x25 RIP: 0033:0x7f7cb82603aa RSP: 002b:00007ffd60770bc8 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: ffffffffffffffda RBX: 00007f7cb6cd4000 RCX: 00007f7cb82603aa RDX: 000000000000000b RSI: 00007ffd60770bd0 RDI: 0000000000007cca RBP: 0000000000007cca R08: 00007f7cb8965700 R09: 00007ffd607c7080 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd60770bd0 R14: 00007f7cb6cd4058 R15: 00000000cccccccd Code: c1 e2 04 44 8b 60 30 48 8b 40 38 44 8b 34 11 48 c7 c2 60 3a f5 81 44 89 e1 4c 8b 68 58 e8 4b b4 77 00 89 44 24 14 48 8d 74 24 10 <49> 8b 7d 00 e8 b9 6a f9 ff 48 85 c0 74 1a 48 89 c7 48 89 44 24 RIP: proc_flush_task+0x8e/0x1b0 RSP: ffffc9000bbffc40 CR2: 0000000000000000 ---[ end trace 53d67a6481059862 ]--- Improve the quality of the implementation by resetting the place to start allocating pids on failure to allocate the first pid. As improving the quality of the implementation is the goal remove the now unnecesarry disable_pid_allocations call when we fail to mount proc. Fixes: 95846ecf9dac ("pid: replace pid bitmap implementation with IDR API") Fixes: 8ef047aaaeb8 ("pid namespaces: make alloc_pid(), free_pid() and put_pid() work with struct upid") Reported-by: Dave Jones Signed-off-by: "Eric W. Biederman"