tjh.dev
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.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1443943
3
927
Clone this repository
https://tangled.org/tjh.dev/kernel
https://tangled.org/did:plc:65gha4t3avpfpzmvpbwovss7/kernel
git@gordian.tjh.dev:tjh.dev/kernel
git@gordian.tjh.dev:did:plc:65gha4t3avpfpzmvpbwovss7/kernel
For self-hosted knots, clone URLs may differ based on your setup.
Download tar.gz
Turning page table entries read-only requires the mmap_sem held for
writing.
So stop doing the odd games with turning things from read locks to write
locks and back. Just get the write lock.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull device mapper fixes from Mike Snitzer:
- Fix DM-raid's raid1 discard limits so discards work.
- Select missing Kconfig dependencies for DM integrity and zoned
targets.
- Four fixes for DM crypt target's support to optionally bypass kcryptd
workqueues.
- Fix DM snapshot merge supports missing data flushes before committing
metadata.
- Fix DM integrity data device flushing when external metadata is used.
- Fix DM integrity's maximum number of supported constructor arguments
that user can request when creating an integrity device.
- Eliminate DM core ioctl logging noise when an ioctl is issued without
required CAP_SYS_RAWIO permission.
* tag 'for-5.11/dm-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm crypt: defer decryption to a tasklet if interrupts disabled
dm integrity: fix the maximum number of arguments
dm crypt: do not call bio_endio() from the dm-crypt tasklet
dm integrity: fix flush with external metadata device
dm: eliminate potential source of excessive kernel log noise
dm snapshot: flush merged data before committing metadata
dm crypt: use GFP_ATOMIC when allocating crypto requests from softirq
dm crypt: do not wait for backlogged crypto request completion in softirq
dm zoned: select CONFIG_CRC32
dm integrity: select CRYPTO_SKCIPHER
dm raid: fix discard limits for raid1
Merge misc fixes from Andrew Morton:
"10 patches.
Subsystems affected by this patch series: MAINTAINERS and mm (slub,
pagealloc, memcg, kasan, vmalloc, migration, hugetlb, memory-failure,
and process_vm_access)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
mm/process_vm_access.c: include compat.h
mm,hwpoison: fix printing of page flags
MAINTAINERS: add Vlastimil as slab allocators maintainer
mm/hugetlb: fix potential missing huge page size info
mm: migrate: initialize err in do_migrate_pages
mm/vmalloc.c: fix potential memory leak
arm/kasan: fix the array size of kasan_early_shadow_pte[]
mm/memcontrol: fix warning in mem_cgroup_page_lruvec()
mm/page_alloc: add a missing mm_page_alloc_zone_locked() tracepoint
mm, slub: consider rest of partial list if acquire_slab() fails
On some specific hardware on early boot we occasionally get:
[ 1193.920255][ T0] BUG: sleeping function called from invalid context at mm/mempool.c:381
[ 1193.936616][ T0] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/69
[ 1193.953233][ T0] no locks held by swapper/69/0.
[ 1193.965871][ T0] irq event stamp: 575062
[ 1193.977724][ T0] hardirqs last enabled at (575061): [<ffffffffab73f662>] tick_nohz_idle_exit+0xe2/0x3e0
[ 1194.002762][ T0] hardirqs last disabled at (575062): [<ffffffffab74e8af>] flush_smp_call_function_from_idle+0x4f/0x80
[ 1194.029035][ T0] softirqs last enabled at (575050): [<ffffffffad600fd2>] asm_call_irq_on_stack+0x12/0x20
[ 1194.054227][ T0] softirqs last disabled at (575043): [<ffffffffad600fd2>] asm_call_irq_on_stack+0x12/0x20
[ 1194.079389][ T0] CPU: 69 PID: 0 Comm: swapper/69 Not tainted 5.10.6-cloudflare-kasan-2021.1.4-dev #1
[ 1194.104103][ T0] Hardware name: NULL R162-Z12-CD/MZ12-HD4-CD, BIOS R10 06/04/2020
[ 1194.119591][ T0] Call Trace:
[ 1194.130233][ T0] dump_stack+0x9a/0xcc
[ 1194.141617][ T0] ___might_sleep.cold+0x180/0x1b0
[ 1194.153825][ T0] mempool_alloc+0x16b/0x300
[ 1194.165313][ T0] ? remove_element+0x160/0x160
[ 1194.176961][ T0] ? blk_mq_end_request+0x4b/0x490
[ 1194.188778][ T0] crypt_convert+0x27f6/0x45f0 [dm_crypt]
[ 1194.201024][ T0] ? rcu_read_lock_sched_held+0x3f/0x70
[ 1194.212906][ T0] ? module_assert_mutex_or_preempt+0x3e/0x70
[ 1194.225318][ T0] ? __module_address.part.0+0x1b/0x3a0
[ 1194.237212][ T0] ? is_kernel_percpu_address+0x5b/0x190
[ 1194.249238][ T0] ? crypt_iv_tcw_ctr+0x4a0/0x4a0 [dm_crypt]
[ 1194.261593][ T0] ? is_module_address+0x25/0x40
[ 1194.272905][ T0] ? static_obj+0x8a/0xc0
[ 1194.283582][ T0] ? lockdep_init_map_waits+0x26a/0x700
[ 1194.295570][ T0] ? __raw_spin_lock_init+0x39/0x110
[ 1194.307330][ T0] kcryptd_crypt_read_convert+0x31c/0x560 [dm_crypt]
[ 1194.320496][ T0] ? kcryptd_queue_crypt+0x1be/0x380 [dm_crypt]
[ 1194.333203][ T0] blk_update_request+0x6d7/0x1500
[ 1194.344841][ T0] ? blk_mq_trigger_softirq+0x190/0x190
[ 1194.356831][ T0] blk_mq_end_request+0x4b/0x490
[ 1194.367994][ T0] ? blk_mq_trigger_softirq+0x190/0x190
[ 1194.379693][ T0] flush_smp_call_function_queue+0x24b/0x560
[ 1194.391847][ T0] flush_smp_call_function_from_idle+0x59/0x80
[ 1194.403969][ T0] do_idle+0x287/0x450
[ 1194.413891][ T0] ? arch_cpu_idle_exit+0x40/0x40
[ 1194.424716][ T0] ? lockdep_hardirqs_on_prepare+0x286/0x3f0
[ 1194.436399][ T0] ? _raw_spin_unlock_irqrestore+0x39/0x40
[ 1194.447759][ T0] cpu_startup_entry+0x19/0x20
[ 1194.458038][ T0] secondary_startup_64_no_verify+0xb0/0xbb
IO completion can be queued to a different CPU by the block subsystem as a "call
single function/data". The CPU may run these routines from the idle task, but it
does so with interrupts disabled.
It is not a good idea to do decryption with irqs disabled even in an idle task
context, so just defer it to a tasklet (as is done with requests from hard irqs).
Fixes: 39d42fa96ba1 ("dm crypt: add flags to optionally bypass kcryptd workqueues")
Cc: stable@vger.kernel.org # v5.9+
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Pull rdma fixes from Jason Gunthorpe:
"A fairly modest set of bug fixes, nothing abnormal from the merge
window
The ucma patch is a bit on the larger side, but given the regression
was recently added I've opted to forward it to the rc stream.
- Fix a ucma memory leak introduced in v5.9 while fixing the
Syzkaller bugs
- Don't fail when the xarray wraps for user verbs objects
- User triggerable oops regression from the umem page size rework
- Error unwind bugs in usnic, ocrdma, mlx5 and cma"
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
RDMA/cma: Fix error flow in default_roce_mode_store
RDMA/mlx5: Fix wrong free of blue flame register on error
IB/mlx5: Fix error unwinding when set_has_smi_cap fails
RDMA/umem: Avoid undefined behavior of rounddown_pow_of_two()
RDMA/ocrdma: Fix use after free in ocrdma_dealloc_ucontext_pd()
RDMA/usnic: Fix memleak in find_free_vf_and_create_qp_grp
RDMA/restrack: Don't treat as an error allocation ID wrapping
RDMA/ucma: Do not miss ctx destruction steps in some cases
Fix the build error:
mm/process_vm_access.c:277:5: error: implicit declaration of function 'in_compat_syscall'; did you mean 'in_ia32_syscall'? [-Werror=implicit-function-declaration]
Fixes: 38dc5079da7081e "Fix compat regression in process_vm_rw()"
Reported-by: syzbot+5b0d0de84d6c65b8dd2b@syzkaller.appspotmail.com
Cc: Kyle Huey <me@kylehuey.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Advance the maximum number of arguments from 9 to 15 to account for
all potential feature flags that may be supplied.
Linux 4.19 added "meta_device"
(356d9d52e1221ba0c9f10b8b38652f78a5298329) and "recalculate"
(a3fcf7253139609bf9ff901fbf955fba047e75dd) flags.
Commit 468dfca38b1a6fbdccd195d875599cb7c8875cd9 added
"sectors_per_bit" and "bitmap_flush_interval".
Commit 84597a44a9d86ac949900441cea7da0af0f2f473 added
"allow_discards".
And the commit d537858ac8aaf4311b51240893add2fc62003b97 added
"fix_padding".
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Pull ext4 fixes from Ted Ts'o:
"A number of bug fixes for ext4:
- Fix for the new fast_commit feature
- Fix some error handling codepaths in whiteout handling and
mountpoint sampling
- Fix how we write ext4_error information so it goes through the
journal when journalling is active, to avoid races that can lead to
lost error information, superblock checksum failures, or DIF/DIX
features"
* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: remove expensive flush on fast commit
ext4: fix bug for rename with RENAME_WHITEOUT
ext4: fix wrong list_splice in ext4_fc_cleanup
ext4: use IS_ERR instead of IS_ERR_OR_NULL and set inode null when IS_ERR
ext4: don't leak old mountpoint samples
ext4: drop ext4_handle_dirty_super()
ext4: fix superblock checksum failure when setting password salt
ext4: use sbi instead of EXT4_SB(sb) in ext4_update_super()
ext4: save error info to sb through journal if available
ext4: protect superblock modifications with a buffer lock
ext4: drop sync argument of ext4_commit_super()
ext4: combine ext4_handle_error() and save_error_info()
In default_roce_mode_store(), we took a reference to cma_dev, but didn't
return it with cma_dev_put in the error flow.
Fixes: 1c15b4f2a42f ("RDMA/core: Modify enum ib_gid_type and enum rdma_network_type")
Link: https://lore.kernel.org/r/20210113130214.562108-1-leon@kernel.org
Signed-off-by: Neta Ostrovsky <netao@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Format %pG expects a lower case 'p' in order to print the flags.
Fix it.
Link: https://lkml.kernel.org/r/20210108085202.4506-1-osalvador@suse.de
Fixes: 8295d535e2aa ("mm,hwpoison: refactor get_any_page")
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sometimes, when dm-crypt executes decryption in a tasklet, we may get
"BUG: KASAN: use-after-free in tasklet_action_common.constprop..."
with a kasan-enabled kernel.
When the decryption fully completes in the tasklet, dm-crypt will call
bio_endio(), which in turn will call clone_endio() from dm.c core code. That
function frees the resources associated with the bio, including per bio private
structures. For dm-crypt it will free the current struct dm_crypt_io, which
contains our tasklet object, causing use-after-free, when the tasklet is being
dequeued by the kernel.
To avoid this, do not call bio_endio() from the current tasklet context, but
delay its execution to the dm-crypt IO workqueue.
Fixes: 39d42fa96ba1 ("dm crypt: add flags to optionally bypass kcryptd workqueues")
Cc: <stable@vger.kernel.org> # v5.9+
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Pull cifs fixes from Steve French:
"Two small cifs fixes for stable (including an important handle leak
fix) and three small cleanup patches"
* tag '5.11-rc3-smb3' of git://git.samba.org/sfrench/cifs-2.6:
cifs: style: replace one-element array with flexible-array
cifs: connect: style: Simplify bool comparison
fs: cifs: remove unneeded variable in smb3_fs_context_dup
cifs: fix interrupted close commands
cifs: check pointer before freeing
In the fast commit, it adds REQ_FUA and REQ_PREFLUSH on each fast
commit block when barrier is enabled. However, in recovery phase,
ext4 compares CRC value in the tail. So it is sufficient to add
REQ_FUA and REQ_PREFLUSH on the block that has tail.
Signed-off-by: Daejun Park <daejun7.park@samsung.com>
Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20210106013242epcms2p5b6b4ed8ca86f29456fdf56aa580e74b4@epcms2p5
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
README