56ee254d23
This reverts commit bbaf9715f3f5b5ff0de71da91fcc34ee9c198ed8. The kmaps in compression code are still needed and cause crashes on 32bit machines (ARM, x86). Reproducible eg. by running fstest btrfs/004 with enabled LZO or ZSTD compression. Example stacktrace with ZSTD on a 32bit ARM machine: Unable to handle kernel NULL pointer dereference at virtual address 00000000 pgd = c4159ed3 [00000000] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 210 Comm: kworker/u2:3 Not tainted 5.14.0-rc79+ #12 Hardware name: Allwinner sun4i/sun5i Families Workqueue: btrfs-delalloc btrfs_work_helper PC is at mmiocpy+0x48/0x330 LR is at ZSTD_compressStream_generic+0x15c/0x28c (mmiocpy) from [<c0629648>] (ZSTD_compressStream_generic+0x15c/0x28c) (ZSTD_compressStream_generic) from [<c06297dc>] (ZSTD_compressStream+0x64/0xa0) (ZSTD_compressStream) from [<c049444c>] (zstd_compress_pages+0x170/0x488) (zstd_compress_pages) from [<c0496798>] (btrfs_compress_pages+0x124/0x12c) (btrfs_compress_pages) from [<c043c068>] (compress_file_range+0x3c0/0x834) (compress_file_range) from [<c043c4ec>] (async_cow_start+0x10/0x28) (async_cow_start) from [<c0475c3c>] (btrfs_work_helper+0x100/0x230) (btrfs_work_helper) from [<c014ef68>] (process_one_work+0x1b4/0x418) (process_one_work) from [<c014f210>] (worker_thread+0x44/0x524) (worker_thread) from [<c0156aa4>] (kthread+0x180/0x1b0) (kthread) from [<c0100150>] Link: https://lore.kernel.org/all/CAJCQCtT+OuemovPO7GZk8Y8=qtOObr0XTDp8jh4OHD6y84AFxw@mail.gmail.com/ Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=214839 Signed-off-by: David Sterba <dsterba@suse.com>
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.