Kent Overstreet 9c18ea7ffe bcachefs: bch2_get_random_u64_below()
steal the (clever) algorithm from get_random_u32_below()

this fixes a bug where we were passing roundup_pow_of_two() a 64 bit
number - we're squaring device latencies now:

[  +1.681698] ------------[ cut here ]------------
[  +0.000010] UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
[  +0.000011] shift exponent 64 is too large for 64-bit type 'long unsigned int'
[  +0.000011] CPU: 1 UID: 0 PID: 196 Comm: kworker/u32:13 Not tainted 6.14.0-rc6-dave+ #10
[  +0.000012] Hardware name: ASUS System Product Name/PRIME B460I-PLUS, BIOS 1301 07/13/2021
[  +0.000005] Workqueue: events_unbound __bch2_read_endio [bcachefs]
[  +0.000354] Call Trace:
[  +0.000005]  <TASK>
[  +0.000007]  dump_stack_lvl+0x5d/0x80
[  +0.000018]  ubsan_epilogue+0x5/0x30
[  +0.000008]  __ubsan_handle_shift_out_of_bounds.cold+0x61/0xe6
[  +0.000011]  bch2_rand_range.cold+0x17/0x20 [bcachefs]
[  +0.000231]  bch2_bkey_pick_read_device+0x547/0x920 [bcachefs]
[  +0.000229]  __bch2_read_extent+0x1e4/0x18e0 [bcachefs]
[  +0.000241]  ? bch2_btree_iter_peek_slot+0x3df/0x800 [bcachefs]
[  +0.000180]  ? bch2_read_retry_nodecode+0x270/0x330 [bcachefs]
[  +0.000230]  bch2_read_retry_nodecode+0x270/0x330 [bcachefs]
[  +0.000230]  bch2_rbio_retry+0x1fa/0x600 [bcachefs]
[  +0.000224]  ? bch2_printbuf_make_room+0x71/0xb0 [bcachefs]
[  +0.000243]  ? bch2_read_csum_err+0x4a4/0x610 [bcachefs]
[  +0.000278]  bch2_read_csum_err+0x4a4/0x610 [bcachefs]
[  +0.000227]  ? __bch2_read_endio+0x58b/0x870 [bcachefs]
[  +0.000220]  __bch2_read_endio+0x58b/0x870 [bcachefs]
[  +0.000268]  ? try_to_wake_up+0x31c/0x7f0
[  +0.000011]  ? process_one_work+0x176/0x330
[  +0.000008]  process_one_work+0x176/0x330
[  +0.000008]  worker_thread+0x252/0x390
[  +0.000008]  ? __pfx_worker_thread+0x10/0x10
[  +0.000006]  kthread+0xec/0x230
[  +0.000011]  ? __pfx_kthread+0x10/0x10
[  +0.000009]  ret_from_fork+0x31/0x50
[  +0.000009]  ? __pfx_kthread+0x10/0x10
[  +0.000008]  ret_from_fork_asm+0x1a/0x30
[  +0.000012]  </TASK>
[  +0.000046] ---[ end trace ]---

Reported-by: Roland Vet <vet.roland@protonmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2025-03-13 12:40:22 -04:00
2025-03-13 12:40:22 -04:00
2024-09-01 20:43:24 -07:00
2025-02-04 11:27:45 -05:00
2022-09-28 09:02:20 +02:00
2025-03-09 13:45:25 -10:00
2024-03-18 03:36:32 -06:00

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 reStructuredText 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.
Description
No description provided
Readme 3.5 GiB
Languages
C 97.1%
Assembly 1%
Shell 0.6%
Rust 0.4%
Python 0.4%
Other 0.3%