1) uml kernel bootmem managed through bootmem_data->node_bootmem_map,
not the struct page array, so the array is unnecessary.
2) the bootmem struct page array has been pointed by a *local* pointer,
struct page *map, in init_maps function. The array can be accessed only
in init_maps's scope. As a result, uml kernel wastes about 1% of total
memory.
Signed-off-by: Honggang Li <enjoymindful@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
If do_ops() fails we have to release current->mm->mmap_sem
otherwise the failing task will never terminate.
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
Trinity discovered an execution path such that a task
can unmap his stub page.
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
The reverse case of this race (you must msync before read) is
well known. This is the not so common one.
It can be triggered only on systems which do a lot of task
switching and only at UML startup. If you are starting 200+ UMLs
~ 0.5% will always die without this fix.
Signed-off-by: Anton Ivanov <antivano@cisco.com>
[rw: minor whitespace fixes]
Signed-off-by: Richard Weinberger <richard@nod.at>
We cannot use print_stack_trace because the name conflicts
with linux/stacktrace.h.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
Pull UML changes from Richard Weinberger:
"This pile contains a nice defconfig cleanup, a rewritten stack
unwinder and various cleanups"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
um: Remove unused declarations from <as-layout.h>
um: remove used STDIO_CONSOLE Kconfig param
um/vdso: add .gitignore for a couple of targets
arch/um: make it work with defconfig and x86_64
um: Make kstack_depth_to_print conform to arch/x86
um: Get rid of thread_struct->saved_task
um: Make stack trace reliable against kernel mode faults
um: Rewrite show_stack()
As UML uses an alternative signal stack we cannot use
the current stack pointer for stack dumping if UML itself
dies by SIGSEGV. To bypass this issue we save regs taken
from mcontext in our segv handler into thread_struct and
use these regs to obtain the stack pointer in show_stack().
Signed-off-by: Richard Weinberger <richard@nod.at>
Currently on UML stack traces are not very reliable and both
x86 and x86_64 have their on implementations.
This patch unifies both and adds support to outline unreliable
functions calls.
Signed-off-by: Richard Weinberger <richard@nod.at>
Unlike global OOM handling, memory cgroup code will invoke the OOM killer
in any OOM situation because it has no way of telling faults occuring in
kernel context - which could be handled more gracefully - from
user-triggered faults.
Pass a flag that identifies faults originating in user space from the
architecture-specific fault handlers to generic code so that memcg OOM
handling can be improved.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: azurIt <azurit@pobox.sk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These handlers are not optional and need in our case
dummy implementions to avoid NULL pointer bugs within
the irq core code.
Reported-and-tested-by: Toralf Foester <toralf.foerster@gmx.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
UML needs it's own probe_kernel_read() to handle kernel
mode faults correctly.
The implementation uses mincore() on the host side to detect
whether a page is owned by the UML kernel process.
This fixes also a possible crash when sysrq-t is used.
Starting with 3.10 sysrq-t calls probe_kernel_read() to
read details from the kernel workers. As kernel worker are
completely async pointers may turn NULL while reading them.
Cc: <stian@nixia.no>
Cc: <tj@kernel.org>
Cc: <stable@vger.kernel.org> # 3.10.x
Signed-off-by: Richard Weinberger <richard@nod.at>
Currently we use both struct siginfo and siginfo_t.
Let's use struct siginfo internally to avoid ongoing
compiler warning. We are allowed to do so because
struct siginfo and siginfo_t are equivalent.
Signed-off-by: Richard Weinberger <richard@nod.at>
Ensure that a process cannot destroy his stub pages with
using MADV_DONTNEED and friends.
Reported-by: toralf.foerster@gmx.de
Signed-off-by: Richard Weinberger <richard@nod.at>
In case of an error it must not return -EFAULT.
Return 0 like all other archs do.
Reported-by: toralf.foerster@gmx.de
Signed-off-by: Richard Weinberger <richard@nod.at>
