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4749ffdfbb
[ Upstream commit ab6c03676c ]
and use smaller/on-stack buffer instead
The motivation for this change was lockdep splat like below.
| potentially unexpected fatal signal 11.
| BUG: sleeping function called from invalid context at ../mm/page_alloc.c:4317
| in_atomic(): 1, irqs_disabled(): 0, pid: 57, name: segv
| no locks held by segv/57.
| Preemption disabled at:
| [<8182f17e>] get_signal+0x4a6/0x7c4
| CPU: 0 PID: 57 Comm: segv Not tainted 4.17.0+ #23
|
| Stack Trace:
| arc_unwind_core.constprop.1+0xd0/0xf4
| __might_sleep+0x1f6/0x234
| __get_free_pages+0x174/0xca0
| show_regs+0x22/0x330
| get_signal+0x4ac/0x7c4 # print_fatal_signals() -> preempt_disable()
| do_signal+0x30/0x224
| resume_user_mode_begin+0x90/0xd8
So signal handling core calls show_regs() with preemption disabled but
an ensuing GFP_KERNEL page allocator call is flagged by lockdep.
We could have switched to GFP_NOWAIT, but turns out that is not enough
anways and eliding page allocator call leads to less code and
instruction traces to sift thru when debugging pesky crashes.
FWIW, this patch doesn't cure the lockdep splat (which next patch does).
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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
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In order to build the documentation, use ``make htmldocs`` or
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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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.