mainlining shenanigans
d1bd7e0ba5
Booting the latest kernel with DEBUG_ATOMIC_SLEEP=y on a GICv4.1 enabled
box, I get the following kernel splat:
[ 0.053766] BUG: sleeping function called from invalid context at mm/slab.h:567
[ 0.053767] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/1
[ 0.053769] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.8.0-rc3+ #23
[ 0.053770] Call trace:
[ 0.053774] dump_backtrace+0x0/0x218
[ 0.053775] show_stack+0x2c/0x38
[ 0.053777] dump_stack+0xc4/0x10c
[ 0.053779] ___might_sleep+0xfc/0x140
[ 0.053780] __might_sleep+0x58/0x90
[ 0.053782] slab_pre_alloc_hook+0x7c/0x90
[ 0.053783] kmem_cache_alloc_trace+0x60/0x2f0
[ 0.053785] its_cpu_init+0x6f4/0xe40
[ 0.053786] gic_starting_cpu+0x24/0x38
[ 0.053788] cpuhp_invoke_callback+0xa0/0x710
[ 0.053789] notify_cpu_starting+0xcc/0xd8
[ 0.053790] secondary_start_kernel+0x148/0x200
# ./scripts/faddr2line vmlinux its_cpu_init+0x6f4/0xe40
its_cpu_init+0x6f4/0xe40:
allocate_vpe_l1_table at drivers/irqchip/irq-gic-v3-its.c:2818
(inlined by) its_cpu_init_lpis at drivers/irqchip/irq-gic-v3-its.c:3138
(inlined by) its_cpu_init at drivers/irqchip/irq-gic-v3-its.c:5166
It turned out that we're allocating memory using GFP_KERNEL (may sleep)
within the CPU hotplug notifier, which is indeed an atomic context. Bad
thing may happen if we're playing on a system with more than a single
CommonLPIAff group. Avoid it by turning this into an atomic allocation.
Fixes:
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||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
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.
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.