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a419beac4a
Using kmalloc() to allocate the decompression workspace for zstd may
trigger the following warning when large modules are loaded (i.e., xfs):
[ 2.961884] WARNING: CPU: 1 PID: 254 at mm/page_alloc.c:4453 __alloc_pages+0x2c3/0x350
...
[ 2.989033] Call Trace:
[ 2.989841] <TASK>
[ 2.990614] ? show_regs+0x6d/0x80
[ 2.991573] ? __warn+0x89/0x160
[ 2.992485] ? __alloc_pages+0x2c3/0x350
[ 2.993520] ? report_bug+0x17e/0x1b0
[ 2.994506] ? handle_bug+0x51/0xa0
[ 2.995474] ? exc_invalid_op+0x18/0x80
[ 2.996469] ? asm_exc_invalid_op+0x1b/0x20
[ 2.997530] ? module_zstd_decompress+0xdc/0x2a0
[ 2.998665] ? __alloc_pages+0x2c3/0x350
[ 2.999695] ? module_zstd_decompress+0xdc/0x2a0
[ 3.000821] __kmalloc_large_node+0x7a/0x150
[ 3.001920] __kmalloc+0xdb/0x170
[ 3.002824] module_zstd_decompress+0xdc/0x2a0
[ 3.003857] module_decompress+0x37/0xc0
[ 3.004688] init_module_from_file+0xd0/0x100
[ 3.005668] idempotent_init_module+0x11c/0x2b0
[ 3.006632] __x64_sys_finit_module+0x64/0xd0
[ 3.007568] do_syscall_64+0x59/0x90
[ 3.008373] ? ksys_read+0x73/0x100
[ 3.009395] ? exit_to_user_mode_prepare+0x30/0xb0
[ 3.010531] ? syscall_exit_to_user_mode+0x37/0x60
[ 3.011662] ? do_syscall_64+0x68/0x90
[ 3.012511] ? do_syscall_64+0x68/0x90
[ 3.013364] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
However, continuous physical memory does not seem to be required in
module_zstd_decompress(), so use vmalloc() instead, to prevent the
warning and avoid potential failures at loading compressed modules.
Fixes: 169a58ad82 ("module/decompress: Support zstd in-kernel decompression")
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Luis Chamberlain <mcgrof@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
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.