linux-stable.git/arch/um, branch v4.19.76

um: Silence lockdep complaint about mmap_sem

2019-07-31T05:27:04+00:00

[ Upstream commit 80bf6ceaf9310b3f61934c69b382d4912deee049 ]

When we get into activate_mm(), lockdep complains that we're doing
something strange:

    WARNING: possible circular locking dependency detected
    5.1.0-10252-gb00152307319-dirty #121 Not tainted
    ------------------------------------------------------
    inside.sh/366 is trying to acquire lock:
    (____ptrval____) (&(&p->alloc_lock)->rlock){+.+.}, at: flush_old_exec+0x703/0x8d7

    but task is already holding lock:
    (____ptrval____) (&mm->mmap_sem){++++}, at: flush_old_exec+0x6c5/0x8d7

    which lock already depends on the new lock.

    the existing dependency chain (in reverse order) is:

    -> #1 (&mm->mmap_sem){++++}:
           [...]
           __lock_acquire+0x12ab/0x139f
           lock_acquire+0x155/0x18e
           down_write+0x3f/0x98
           flush_old_exec+0x748/0x8d7
           load_elf_binary+0x2ca/0xddb
           [...]

    -> #0 (&(&p->alloc_lock)->rlock){+.+.}:
           [...]
           __lock_acquire+0x12ab/0x139f
           lock_acquire+0x155/0x18e
           _raw_spin_lock+0x30/0x83
           flush_old_exec+0x703/0x8d7
           load_elf_binary+0x2ca/0xddb
           [...]

    other info that might help us debug this:

     Possible unsafe locking scenario:

           CPU0                    CPU1
           ----                    ----
      lock(&mm->mmap_sem);
                                   lock(&(&p->alloc_lock)->rlock);
                                   lock(&mm->mmap_sem);
      lock(&(&p->alloc_lock)->rlock);

     *** DEADLOCK ***

    2 locks held by inside.sh/366:
     #0: (____ptrval____) (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file+0x12d/0x869
     #1: (____ptrval____) (&mm->mmap_sem){++++}, at: flush_old_exec+0x6c5/0x8d7

    stack backtrace:
    CPU: 0 PID: 366 Comm: inside.sh Not tainted 5.1.0-10252-gb00152307319-dirty #121
    Stack:
     [...]
    Call Trace:
     [<600420de>] show_stack+0x13b/0x155
     [<6048906b>] dump_stack+0x2a/0x2c
     [<6009ae64>] print_circular_bug+0x332/0x343
     [<6009c5c6>] check_prev_add+0x669/0xdad
     [<600a06b4>] __lock_acquire+0x12ab/0x139f
     [<6009f3d0>] lock_acquire+0x155/0x18e
     [<604a07e0>] _raw_spin_lock+0x30/0x83
     [<60151e6a>] flush_old_exec+0x703/0x8d7
     [<601a8eb8>] load_elf_binary+0x2ca/0xddb
     [...]

I think it's because in exec_mmap() we have

	down_read(&old_mm->mmap_sem);
...
        task_lock(tsk);
...
	activate_mm(active_mm, mm);
	(which does down_write(&mm->mmap_sem))

I'm not really sure why lockdep throws in the whole knowledge
about the task lock, but it seems that old_mm and mm shouldn't
ever be the same (and it doesn't deadlock) so tell lockdep that
they're different.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger 
Signed-off-by: Sasha Levin

uml: fix a boot splat wrt use of cpu_all_mask

2019-06-15T09:54:05+00:00

[ Upstream commit 689a58605b63173acb0a8cf954af6a8f60440c93 ]

Memory: 509108K/542612K available (3835K kernel code, 919K rwdata, 1028K rodata, 129K init, 211K bss, 33504K reserved, 0K cma-reserved)
NR_IRQS: 15
clocksource: timer: mask: 0xffffffffffffffff max_cycles: 0x1cd42e205, max_idle_ns: 881590404426 ns
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at kernel/time/clockevents.c:458 clockevents_register_device+0x72/0x140
posix-timer cpumask == cpu_all_mask, using cpu_possible_mask instead
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 5.1.0-rc4-00048-ged79cc87302b #4
Stack:
 604ebda0 603c5370 604ebe20 6046fd17
 00000000 6006fcbb 604ebdb0 603c53b5
 604ebe10 6003bfc4 604ebdd0 9000001ca
Call Trace:
 [<6006fcbb>] ? printk+0x0/0x94
 [<60083160>] ? clockevents_register_device+0x72/0x140
 [<6001f16e>] show_stack+0x13b/0x155
 [<603c5370>] ? dump_stack_print_info+0xe2/0xeb
 [<6006fcbb>] ? printk+0x0/0x94
 [<603c53b5>] dump_stack+0x2a/0x2c
 [<6003bfc4>] __warn+0x10e/0x13e
 [<60070320>] ? vprintk_func+0xc8/0xcf
 [<60030fd6>] ? block_signals+0x0/0x16
 [<6006fcbb>] ? printk+0x0/0x94
 [<6003c08b>] warn_slowpath_fmt+0x97/0x99
 [<600311a1>] ? set_signals+0x0/0x3f
 [<6003bff4>] ? warn_slowpath_fmt+0x0/0x99
 [<600842cb>] ? tick_oneshot_mode_active+0x44/0x4f
 [<60030fd6>] ? block_signals+0x0/0x16
 [<6006fcbb>] ? printk+0x0/0x94
 [<6007d2d5>] ? __clocksource_select+0x20/0x1b1
 [<60030fd6>] ? block_signals+0x0/0x16
 [<6006fcbb>] ? printk+0x0/0x94
 [<60083160>] clockevents_register_device+0x72/0x140
 [<60031192>] ? get_signals+0x0/0xf
 [<60030fd6>] ? block_signals+0x0/0x16
 [<6006fcbb>] ? printk+0x0/0x94
 [<60002eec>] um_timer_setup+0xc8/0xca
 [<60001b59>] start_kernel+0x47f/0x57e
 [<600035bc>] start_kernel_proc+0x49/0x4d
 [<6006c483>] ? kmsg_dump_register+0x82/0x8a
 [<6001de62>] new_thread_handler+0x81/0xb2
 [<60003571>] ? kmsg_dumper_stdout_init+0x1a/0x1c
 [<60020c75>] uml_finishsetup+0x54/0x59

random: get_random_bytes called from init_oops_id+0x27/0x34 with crng_init=0
---[ end trace 00173d0117a88acb ]---
Calibrating delay loop... 6941.90 BogoMIPS (lpj=34709504)

Signed-off-by: Maciej Żenczykowski 
Cc: Jeff Dike 
Cc: Richard Weinberger 
Cc: Anton Ivanov 
Cc: linux-um@lists.infradead.org
Cc: linux-kernel@vger.kernel.org

Signed-off-by: Richard Weinberger 
Signed-off-by: Sasha Levin

um: Don't hardcode path as it is architecture dependent

2019-05-16T17:41:28+00:00

commit 9ca19a3a3e2482916c475b90f3d7fa2a03d8e5ed upstream.

The current code fails to run on amd64 because of hardcoded reference to
i386

Signed-off-by: Ritesh Raj Sarraf 
Signed-off-by: Richard Weinberger 
Signed-off-by: Greg Kroah-Hartman

um: Avoid marking pages with "changed protection"

2019-02-12T18:47:17+00:00

[ Upstream commit 8892d8545f2d0342b9c550defbfb165db237044b ]

Changing protection is a very high cost operation in UML
because in addition to an extra syscall it also interrupts
mmap merge sequences generated by the tlb.

While the condition is not particularly common it is worth
avoiding.

Signed-off-by: Anton Ivanov 
Signed-off-by: Richard Weinberger 
Signed-off-by: Sasha Levin

um: Give start_idle_thread() a return code

2018-11-27T15:12:59+00:00

[ Upstream commit 7ff1e34bbdc15acab823b1ee4240e94623d50ee8 ]

Fixes:
arch/um/os-Linux/skas/process.c:613:1: warning: control reaches end of
non-void function [-Wreturn-type]

longjmp() never returns but gcc still warns that the end of the function
can be reached.
Add a return code and debug aid to detect this impossible case.

Signed-off-by: Richard Weinberger 
Signed-off-by: Sasha Levin

kbuild: rename LDFLAGS to KBUILD_LDFLAGS

2018-08-23T23:22:08+00:00

Commit a0f97e06a43c ("kbuild: enable 'make CFLAGS=...' to add
additional options to CC") renamed CFLAGS to KBUILD_CFLAGS.

Commit 222d394d30e7 ("kbuild: enable 'make AFLAGS=...' to add
additional options to AS") renamed AFLAGS to KBUILD_AFLAGS.

Commit 06c5040cdb13 ("kbuild: enable 'make CPPFLAGS=...' to add
additional options to CPP") renamed CPPFLAGS to KBUILD_CPPFLAGS.

For some reason, LDFLAGS was not renamed.

Using a well-known variable like LDFLAGS may result in accidental
override of the variable.

Kbuild generally uses KBUILD_ prefixed variables for the internally
appended options, so here is one more conversion to sanitize the
naming convention.

I did not touch Makefiles under tools/ since the tools build system
is a different world.

Signed-off-by: Masahiro Yamada 
Acked-by: Kirill A. Shutemov 
Reviewed-by: Palmer Dabbelt

mm: convert return type of handle_mm_fault() caller to vm_fault_t

2018-08-17T23:20:28+00:00

Use new return type vm_fault_t for fault handler.  For now, this is just
documenting that the function returns a VM_FAULT value rather than an
errno.  Once all instances are converted, vm_fault_t will become a
distinct type.

Ref-> commit 1c8f422059ae ("mm: change return type to vm_fault_t")

In this patch all the caller of handle_mm_fault() are changed to return
vm_fault_t type.

Link: http://lkml.kernel.org/r/20180617084810.GA6730@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder 
Cc: Matthew Wilcox 
Cc: Richard Henderson 
Cc: Tony Luck 
Cc: Matt Turner 
Cc: Vineet Gupta 
Cc: Russell King 
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Richard Kuo 
Cc: Geert Uytterhoeven 
Cc: Michal Simek 
Cc: James Hogan 
Cc: Ley Foon Tan 
Cc: Jonas Bonn 
Cc: James E.J. Bottomley 
Cc: Benjamin Herrenschmidt 
Cc: Palmer Dabbelt 
Cc: Yoshinori Sato 
Cc: David S. Miller 
Cc: Richard Weinberger 
Cc: Guan Xuetao 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Cc: "Levin, Alexander (Sasha Levin)" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'kconfig-v4.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2018-08-15T20:05:12+00:00

Pull Kconfig consolidation from Masahiro Yamada:
 "Consolidation of Kconfig files by Christoph Hellwig.

  Move the source statements of arch-independent Kconfig files instead
  of duplicating the includes in every arch/$(SRCARCH)/Kconfig"

* tag 'kconfig-v4.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kconfig: add a Memory Management options" menu
  kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt
  kconfig: use a menu in arch/Kconfig to reduce clutter
  kconfig: include kernel/Kconfig.preempt from init/Kconfig
  Kconfig: consolidate the "Kernel hacking" menu
  kconfig: include common Kconfig files from top-level Kconfig
  kconfig: remove duplicate SWAP symbol defintions
  um: create a proper drivers Kconfig
  um: cleanup Kconfig files
  um: stop abusing KBUILD_KCONFIG

um: clean up archheaders recipe

2018-08-07T12:30:36+00:00

Now that '%asm-generic' is added to no-dot-config-targets,
'make asm-generic' does not include the kernel configuration.

You can simply do 'make asm-generic' in the recursed top Makefile
without bothering syncconfig.

Signed-off-by: Masahiro Yamada 
Tested-by: Randy Dunlap 
Acked-by: Richard Weinberger

um: fix parallel building with O= option

2018-08-07T12:30:15+00:00

Randy Dunlap reports UML occasionally fails to build with -j and
O= options.

  make[1]: Entering directory '/home/rdunlap/mmotm-2018-0802-1529/UM64'
    UPD     include/generated/uapi/linux/version.h
    WRAP    arch/x86/include/generated/asm/dma-contiguous.h
    WRAP    arch/x86/include/generated/asm/export.h
    WRAP    arch/x86/include/generated/asm/early_ioremap.h
    WRAP    arch/x86/include/generated/asm/mcs_spinlock.h
    WRAP    arch/x86/include/generated/asm/mm-arch-hooks.h
    WRAP    arch/x86/include/generated/uapi/asm/bpf_perf_event.h
    WRAP    arch/x86/include/generated/uapi/asm/poll.h
    GEN     ./Makefile
  make[2]: *** No rule to make target 'archheaders'.  Stop.
  arch/um/Makefile:119: recipe for target 'archheaders' failed
  make[1]: *** [archheaders] Error 2
  make[1]: *** Waiting for unfinished jobs....
    UPD     include/config/kernel.release
  make[1]: *** wait: No child processes.  Stop.
  Makefile:146: recipe for target 'sub-make' failed
  make: *** [sub-make] Error 2

The cause of the problem is the use of '$(MAKE) KBUILD_SRC=',
which recurses to the top Makefile via the $(objtree)/Makefile
generated by scripts/mkmakefile.

When you run "make -j O= ARCH=um", Make can execute
'archheaders' and 'outputmakefile' targets simultaneously because
there is no dependency between them.

If it happens,

  $(Q)$(MAKE) KBUILD_SRC= ARCH=$(HEADER_ARCH) archheaders

... tries to run $(objtree)/Makefile that is being updated.

The correct way for the recursion is

  $(Q)$(MAKE) -f $(srctree)/Makefile ARCH=$(HEADER_ARCH) archheaders

..., which does not rely on the generated Makefile.

Reported-by: Randy Dunlap 
Signed-off-by: Masahiro Yamada 
Tested-by: Randy Dunlap 
Acked-by: Richard Weinberger