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Commit ecedd3d7e199 ("block, bfq: get extra ref to prevent a queue
from being freed during a group move") gets an extra reference to a
bfq_queue before possibly deactivating it (temporarily), in
bfq_bfqq_move(). This prevents the bfq_queue from disappearing before
being reactivated in its new group.
Yet, the bfq_queue may also be expired (i.e., its service may be
stopped) before the bfq_queue is deactivated. And also an expiration
may lead to a premature freeing. This commit fixes this issue by
simply moving forward the getting of the extra reference already
introduced by commit ecedd3d7e199 ("block, bfq: get extra ref to
prevent a queue from being freed during a group move").
Reported-by: cki-project@redhat.com
Tested-by: cki-project@redhat.com
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In bfq_idle_slice_timer func, bfqq = bfqd->in_service_queue is
not in bfqd-lock critical section. The bfqq, which is not
equal to NULL in bfq_idle_slice_timer, may be freed after passing
to bfq_idle_slice_timer_body. So we will access the freed memory.
In addition, considering the bfqq may be in race, we should
firstly check whether bfqq is in service before doing something
on it in bfq_idle_slice_timer_body func. If the bfqq in race is
not in service, it means the bfqq has been expired through
__bfq_bfqq_expire func, and wait_request flags has been cleared in
__bfq_bfqd_reset_in_service func. So we do not need to re-clear the
wait_request of bfqq which is not in service.
KASAN log is given as follows:
[13058.354613] ==================================================================
[13058.354640] BUG: KASAN: use-after-free in bfq_idle_slice_timer+0xac/0x290
[13058.354644] Read of size 8 at addr ffffa02cf3e63f78 by task fork13/19767
[13058.354646]
[13058.354655] CPU: 96 PID: 19767 Comm: fork13
[13058.354661] Call trace:
[13058.354667] dump_backtrace+0x0/0x310
[13058.354672] show_stack+0x28/0x38
[13058.354681] dump_stack+0xd8/0x108
[13058.354687] print_address_description+0x68/0x2d0
[13058.354690] kasan_report+0x124/0x2e0
[13058.354697] __asan_load8+0x88/0xb0
[13058.354702] bfq_idle_slice_timer+0xac/0x290
[13058.354707] __hrtimer_run_queues+0x298/0x8b8
[13058.354710] hrtimer_interrupt+0x1b8/0x678
[13058.354716] arch_timer_handler_phys+0x4c/0x78
[13058.354722] handle_percpu_devid_irq+0xf0/0x558
[13058.354731] generic_handle_irq+0x50/0x70
[13058.354735] __handle_domain_irq+0x94/0x110
[13058.354739] gic_handle_irq+0x8c/0x1b0
[13058.354742] el1_irq+0xb8/0x140
[13058.354748] do_wp_page+0x260/0xe28
[13058.354752] __handle_mm_fault+0x8ec/0x9b0
[13058.354756] handle_mm_fault+0x280/0x460
[13058.354762] do_page_fault+0x3ec/0x890
[13058.354765] do_mem_abort+0xc0/0x1b0
[13058.354768] el0_da+0x24/0x28
[13058.354770]
[13058.354773] Allocated by task 19731:
[13058.354780] kasan_kmalloc+0xe0/0x190
[13058.354784] kasan_slab_alloc+0x14/0x20
[13058.354788] kmem_cache_alloc_node+0x130/0x440
[13058.354793] bfq_get_queue+0x138/0x858
[13058.354797] bfq_get_bfqq_handle_split+0xd4/0x328
[13058.354801] bfq_init_rq+0x1f4/0x1180
[13058.354806] bfq_insert_requests+0x264/0x1c98
[13058.354811] blk_mq_sched_insert_requests+0x1c4/0x488
[13058.354818] blk_mq_flush_plug_list+0x2d4/0x6e0
[13058.354826] blk_flush_plug_list+0x230/0x548
[13058.354830] blk_finish_plug+0x60/0x80
[13058.354838] read_pages+0xec/0x2c0
[13058.354842] __do_page_cache_readahead+0x374/0x438
[13058.354846] ondemand_readahead+0x24c/0x6b0
[13058.354851] page_cache_sync_readahead+0x17c/0x2f8
[13058.354858] generic_file_buffered_read+0x588/0xc58
[13058.354862] generic_file_read_iter+0x1b4/0x278
[13058.354965] ext4_file_read_iter+0xa8/0x1d8 [ext4]
[13058.354972] __vfs_read+0x238/0x320
[13058.354976] vfs_read+0xbc/0x1c0
[13058.354980] ksys_read+0xdc/0x1b8
[13058.354984] __arm64_sys_read+0x50/0x60
[13058.354990] el0_svc_common+0xb4/0x1d8
[13058.354994] el0_svc_handler+0x50/0xa8
[13058.354998] el0_svc+0x8/0xc
[13058.354999]
[13058.355001] Freed by task 19731:
[13058.355007] __kasan_slab_free+0x120/0x228
[13058.355010] kasan_slab_free+0x10/0x18
[13058.355014] kmem_cache_free+0x288/0x3f0
[13058.355018] bfq_put_queue+0x134/0x208
[13058.355022] bfq_exit_icq_bfqq+0x164/0x348
[13058.355026] bfq_exit_icq+0x28/0x40
[13058.355030] ioc_exit_icq+0xa0/0x150
[13058.355035] put_io_context_active+0x250/0x438
[13058.355038] exit_io_context+0xd0/0x138
[13058.355045] do_exit+0x734/0xc58
[13058.355050] do_group_exit+0x78/0x220
[13058.355054] __wake_up_parent+0x0/0x50
[13058.355058] el0_svc_common+0xb4/0x1d8
[13058.355062] el0_svc_handler+0x50/0xa8
[13058.355066] el0_svc+0x8/0xc
[13058.355067]
[13058.355071] The buggy address belongs to the object at ffffa02cf3e63e70#012 which belongs to the cache bfq_queue of size 464
[13058.355075] The buggy address is located 264 bytes inside of#012 464-byte region [ffffa02cf3e63e70, ffffa02cf3e64040)
[13058.355077] The buggy address belongs to the page:
[13058.355083] page:ffff7e80b3cf9800 count:1 mapcount:0 mapping:ffff802db5c90780 index:0xffffa02cf3e606f0 compound_mapcount: 0
[13058.366175] flags: 0x2ffffe0000008100(slab|head)
[13058.370781] raw: 2ffffe0000008100 ffff7e80b53b1408 ffffa02d730c1c90 ffff802db5c90780
[13058.370787] raw: ffffa02cf3e606f0 0000000000370023 00000001ffffffff 0000000000000000
[13058.370789] page dumped because: kasan: bad access detected
[13058.370791]
[13058.370792] Memory state around the buggy address:
[13058.370797] ffffa02cf3e63e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fb fb
[13058.370801] ffffa02cf3e63e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[13058.370805] >ffffa02cf3e63f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[13058.370808] ^
[13058.370811] ffffa02cf3e63f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[13058.370815] ffffa02cf3e64000: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
[13058.370817] ==================================================================
[13058.370820] Disabling lock debugging due to kernel taint
Here, we directly pass the bfqd to bfq_idle_slice_timer_body func.
--
V2->V3: rewrite the comment as suggested by Paolo Valente
V1->V2: add one comment, and add Fixes and Reported-by tag.
Fixes: aee69d78d ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler")
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Reported-by: Wang Wang <wangwang2@huawei.com>
Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Signed-off-by: Feilong Lin <linfeilong@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Commit bbbdeb4720a0 ("io_uring: dual license io_uring.h uapi header")
uses a nested SPDX-License-Identifier to dual license the header.
Since then, ./scripts/spdxcheck.py complains:
include/uapi/linux/io_uring.h: 1:60 Missing parentheses: OR
Add parentheses to make spdxcheck.py happy.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pull block fixes from Jens Axboe:
"Just two NVMe fabrics fixes that should go into 5.6"
* tag 'block-5.6-20200320' of git://git.kernel.dk/linux-block:
nvmet-tcp: set MSG_MORE only if we actually have more to send
nvme-rdma: Avoid double freeing of async event data
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Pull io_uring fixes from Jens Axboe:
"Two different fixes in here:
- Fix for a potential NULL pointer deref for links with async or
drain marked (Pavel)
- Fix for not properly checking RLIMIT_NOFILE for async punted
operations.
This affects openat/openat2, which were added this cycle, and
accept4. I did a full audit of other cases where we might check
current->signal->rlim[] and found only RLIMIT_FSIZE for buffered
writes and fallocate. That one is fixed and queued for 5.7 and
marked stable"
* tag 'io_uring-5.6-20200320' of git://git.kernel.dk/linux-block:
io_uring: make sure accept honor rlimit nofile
io_uring: make sure openat/openat2 honor rlimit nofile
io_uring: NULL-deref for IOSQE_{ASYNC,DRAIN}
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git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux
Pull turbostat updates from Len Brown:
"Update to turbostat v20.03.20.
These patches unlock the full turbostat features for some new
machines, plus a couple other minor tweaks"
* 'turbostat' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux:
tools/power turbostat: update version
tools/power turbostat: Print cpuidle information
tools/power turbostat: Fix 32-bit capabilities warning
tools/power turbostat: Fix missing SYS_LPI counter on some Chromebooks
tools/power turbostat: Support Elkhart Lake
tools/power turbostat: Support Jasper Lake
tools/power turbostat: Support Ice Lake server
tools/power turbostat: Support Tiger Lake
tools/power turbostat: Fix gcc build warnings
tools/power turbostat: Support Cometlake
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The futex UAPI changed back in commit 76b81e2b0e22 ("[PATCH] lightweight
robust futexes updates 2"), which landed in v2.6.17: FUTEX_TID_MASK is now
0x3fffffff instead of 0x1fffffff. Update the corresponding comment in
include/linux/threads.h.
Documentation mentions that only the lower 29 bits are available for TID
storage, but as the UAPI header released the bit already via
FUTEX_TID_MASK, this is moot as well. Fix it up.
[ tglx: Fixed up documentation ]
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200302112939.8068-1-jannh@google.com
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The handling of notify->work did not properly maintain notify->kref in two
cases:
1) where the work was already scheduled, another irq_set_affinity_locked()
would get the ref and (no-op-ly) schedule the work. Thus when
irq_affinity_notify() ran, it would drop the original ref but not the
additional one.
2) when cancelling the (old) work in irq_set_affinity_notifier(), if there
was outstanding work a ref had been got for it but was never put.
Fix both by checking the return values of the work handling functions
(schedule_work() for (1) and cancel_work_sync() for (2)) and put the
extra ref if the return value indicates preexisting work.
Fixes: cd7eab44e994 ("genirq: Add IRQ affinity notifiers")
Fixes: 59c39840f5ab ("genirq: Prevent use-after-free and work list corruption")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ben Hutchings <ben@decadent.org.uk>
Link: https://lkml.kernel.org/r/24f5983f-2ab5-e83a-44ee-a45b5f9300f5@solarflare.com
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git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman:
"Two fixes for bugs introduced this cycle:
- fix a crash when shutting down a KVM PR guest (our original style
of KVM which doesn't use hypervisor mode)
- fix for the recently added 32-bit KASAN_VMALLOC support
Thanks to: Christophe Leroy, Greg Kurz, Sean Christopherson"
* tag 'powerpc-5.6-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
KVM: PPC: Fix kernel crash with PR KVM
powerpc/kasan: Fix shadow memory protection with CONFIG_KASAN_VMALLOC
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Continue what commit:
d820ac4c2fa8 ("locking: rename trace_softirq_[enter|exit] => lockdep_softirq_[enter|exit]")
started, rename these to avoid confusing them with tracepoints.
git grep -l "trace_\(soft\|hard\)\(irq_context\|irqs_enabled\)" | while read file;
do
sed -ie 's/trace_\(soft\|hard\)\(irq_context\|irqs_enabled\)/lockdep_\1\2/g' $file;
done
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/20200320115859.178626842@infradead.org
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Continue what commit:
d820ac4c2fa8 ("locking: rename trace_softirq_[enter|exit] => lockdep_softirq_[enter|exit]")
started, rename these to avoid confusing them with tracepoints.
git grep -l "trace_softirqs_\(on\|off\)" | while read file;
do
sed -ie 's/trace_softirqs_\(on\|off\)/lockdep_softirqs_\1/g' $file;
done
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/20200320115859.119434738@infradead.org
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Continue what commit:
d820ac4c2fa8 ("locking: rename trace_softirq_[enter|exit] => lockdep_softirq_[enter|exit]")
started, rename these to avoid confusing them with tracepoints.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/20200320115859.060481361@infradead.org
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Because moar '_' isn't always moar readable.
git grep -l "___preempt_schedule\(_notrace\)*" | while read file;
do
sed -ie 's/___preempt_schedule\(_notrace\)*/preempt_schedule\1_thunk/g' $file;
done
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/20200320115858.995685950@infradead.org
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Clean up includes of and in <asm/syscalls.h>
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-19-brgerst@gmail.com
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asmlinkage is no longer required since the syscall ABI is now fully under
x86 architecture control. This makes the 32-bit native syscalls a bit more
effecient by passing in regs via EAX instead of on the stack.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200313195144.164260-18-brgerst@gmail.com
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Enable pt_regs based syscalls for 32-bit. This makes the 32-bit native
kernel consistent with the 64-bit kernel, and improves the syscall
interface by not needing to push all 6 potential arguments onto the stack.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-17-brgerst@gmail.com
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For the 32-bit syscall interface, 64-bit arguments (loff_t) are passed via
a pair of 32-bit registers. These register pairs end up in consecutive stack
slots, which matches the C ABI for 64-bit arguments. But when accessing the
registers directly from pt_regs, the wrapper needs to manually reassemble the
64-bit value. These wrappers already exist for 32-bit compat, so make them
available to 32-bit native in preparation for enabling pt_regs-based syscalls.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-16-brgerst@gmail.com
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Rename the syscalls that only exist for 32-bit from x86_* to ia32_* to make it
clear they are for 32-bit only. Also rename the functions to match the syscall
name.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-15-brgerst@gmail.com
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After removal of the __ia32_ prefix, remove compat entries that are now
identical to the native entry.
Converted with this script and fixing up whitespace:
while read nr abi name entry compat; do
if [ "${nr:0:1}" = "#" ]; then
echo $nr $abi $name $entry $compat
continue
fi
if [ "$entry" = "$compat" ]; then
compat=""
fi
echo "$nr $abi $name $entry $compat"
done
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-14-brgerst@gmail.com
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Move the ABI prefixes to the __SYSCALL_[abi]() macros. This allows removal
of the need to strip the prefix for UML.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-13-brgerst@gmail.com
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Add a __SYSCALL_COMMON() macro to the syscall table, which simplifies syscalltbl.sh.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-12-brgerst@gmail.com
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Syscall qualifier support is no longer needed.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-11-brgerst@gmail.com
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Now that the fast syscall path is removed, the ptregs qualifier is unused.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-10-brgerst@gmail.com
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Instead of using an array in asm-offsets to calculate the max syscall
number, calculate it when writing out the syscall headers.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-9-brgerst@gmail.com
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Since X32 has its own syscall table now, move it to a separate file.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lkml.kernel.org/r/20200313195144.164260-8-brgerst@gmail.com
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so it can be available to multiple syscall tables. Also directly return
-ENOSYS instead of bouncing to the generic sys_ni_syscall().
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200313195144.164260-7-brgerst@gmail.com
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Add missing syscall wrapper for x32_rt_sigreturn().
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200313195144.164260-6-brgerst@gmail.com
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Pull the common code out from the SYS_NI macros into a new __SYS_NI macro.
Also conditionalize the X64 version in preparation for enabling syscall
wrappers on 32-bit native kernels.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200313195144.164260-5-brgerst@gmail.com
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Pull the common code out from the COND_SYSCALL macros into a new
__COND_SYSCALL macro. Also conditionalize the X64 version in preparation
for enabling syscall wrappers on 32-bit native kernels.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200313195144.164260-4-brgerst@gmail.com
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Pull the common code out from the SYSCALL_DEFINE0 macros into a new
__SYS_STUB0 macro. Also conditionalize the X64 version in preparation for
enabling syscall wrappers on 32-bit native kernels.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200313195144.164260-3-brgerst@gmail.com
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Pull the common code out from the SYSCALL_DEFINEx macros into a new
__SYS_STUBx macro. Also conditionalize the X64 version in preparation for
enabling syscall wrappers on 32-bit native kernels.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200313195144.164260-2-brgerst@gmail.com
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Splitting run_posix_cpu_timers() into two parts is work in progress which
is stuck on other entry code related problems. The heavy lifting which
involves locking of sighand lock will be moved into task context so the
necessary execution time is burdened on the task and not on interrupt
context.
Until this work completes lockdep with the spinlock nesting rules enabled
would emit warnings for this known context.
Prevent it by setting "->irq_config = 1" for the invocation of
run_posix_cpu_timers() so lockdep does not complain when sighand lock is
acquried. This will be removed once the split is completed.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.751182723@linutronix.de
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Mark irq_work items with IRQ_WORK_HARD_IRQ which should be invoked in
hardirq context even on PREEMPT_RT. IRQ_WORK without this flag will be
invoked in softirq context on PREEMPT_RT.
Set ->irq_config to 1 for the IRQ_WORK items which are invoked in softirq
context so lockdep knows that these can safely acquire a spinlock_t.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.643576700@linutronix.de
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Set current->irq_config = 1 for hrtimers which are not marked to expire in
hard interrupt context during hrtimer_init(). These timers will expire in
softirq context on PREEMPT_RT.
Setting this allows lockdep to differentiate these timers. If a timer is
marked to expire in hard interrupt context then the timer callback is not
supposed to acquire a regular spinlock instead of a raw_spinlock in the
expiry callback.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.534508206@linutronix.de
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Extend lockdep to validate lock wait-type context.
The current wait-types are:
LD_WAIT_FREE, /* wait free, rcu etc.. */
LD_WAIT_SPIN, /* spin loops, raw_spinlock_t etc.. */
LD_WAIT_CONFIG, /* CONFIG_PREEMPT_LOCK, spinlock_t etc.. */
LD_WAIT_SLEEP, /* sleeping locks, mutex_t etc.. */
Where lockdep validates that the current lock (the one being acquired)
fits in the current wait-context (as generated by the held stack).
This ensures that there is no attempt to acquire mutexes while holding
spinlocks, to acquire spinlocks while holding raw_spinlocks and so on. In
other words, its a more fancy might_sleep().
Obviously RCU made the entire ordeal more complex than a simple single
value test because RCU can be acquired in (pretty much) any context and
while it presents a context to nested locks it is not the same as it
got acquired in.
Therefore its necessary to split the wait_type into two values, one
representing the acquire (outer) and one representing the nested context
(inner). For most 'normal' locks these two are the same.
[ To make static initialization easier we have the rule that:
.outer == INV means .outer == .inner; because INV == 0. ]
It further means that its required to find the minimal .inner of the held
stack to compare against the outer of the new lock; because while 'normal'
RCU presents a CONFIG type to nested locks, if it is taken while already
holding a SPIN type it obviously doesn't relax the rules.
Below is an example output generated by the trivial test code:
raw_spin_lock(&foo);
spin_lock(&bar);
spin_unlock(&bar);
raw_spin_unlock(&foo);
[ BUG: Invalid wait context ]
-----------------------------
swapper/0/1 is trying to lock:
ffffc90000013f20 (&bar){....}-{3:3}, at: kernel_init+0xdb/0x187
other info that might help us debug this:
1 lock held by swapper/0/1:
#0: ffffc90000013ee0 (&foo){+.+.}-{2:2}, at: kernel_init+0xd1/0x187
The way to read it is to look at the new -{n,m} part in the lock
description; -{3:3} for the attempted lock, and try and match that up to
the held locks, which in this case is the one: -{2,2}.
This tells that the acquiring lock requires a more relaxed environment than
presented by the lock stack.
Currently only the normal locks and RCU are converted, the rest of the
lockdep users defaults to .inner = INV which is ignored. More conversions
can be done when desired.
The check for spinlock_t nesting is not enabled by default. It's a separate
config option for now as there are known problems which are currently
addressed. The config option allows to identify these problems and to
verify that the solutions found are indeed solving them.
The config switch will be removed and the checks will permanently enabled
once the vast majority of issues has been addressed.
[ bigeasy: Move LD_WAIT_FREE,… out of CONFIG_LOCKDEP to avoid compile
failure with CONFIG_DEBUG_SPINLOCK + !CONFIG_LOCKDEP]
[ tglx: Add the config option ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.427089655@linutronix.de
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completion uses a wait_queue_head_t to enqueue waiters.
wait_queue_head_t contains a spinlock_t to protect the list of waiters
which excludes it from being used in truly atomic context on a PREEMPT_RT
enabled kernel.
The spinlock in the wait queue head cannot be replaced by a raw_spinlock
because:
- wait queues can have custom wakeup callbacks, which acquire other
spinlock_t locks and have potentially long execution times
- wake_up() walks an unbounded number of list entries during the wake up
and may wake an unbounded number of waiters.
For simplicity and performance reasons complete() should be usable on
PREEMPT_RT enabled kernels.
completions do not use custom wakeup callbacks and are usually single
waiter, except for a few corner cases.
Replace the wait queue in the completion with a simple wait queue (swait),
which uses a raw_spinlock_t for protecting the waiter list and therefore is
safe to use inside truly atomic regions on PREEMPT_RT.
There is no semantical or functional change:
- completions use the exclusive wait mode which is what swait provides
- complete() wakes one exclusive waiter
- complete_all() wakes all waiters while holding the lock which protects
the wait queue against newly incoming waiters. The conversion to swait
preserves this behaviour.
complete_all() might cause unbound latencies with a large number of waiters
being woken at once, but most complete_all() usage sites are either in
testing or initialization code or have only a really small number of
concurrent waiters which for now does not cause a latency problem. Keep it
simple for now.
The fixup of the warning check in the USB gadget driver is just a straight
forward conversion of the lockless waiter check from one waitqueue type to
the other.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200321113242.317954042@linutronix.de
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As a preparation to use simple wait queues for completions:
- Provide swake_up_all_locked() to support complete_all()
- Make __prepare_to_swait() public available
This is done to enable the usage of complete() within truly atomic contexts
on a PREEMPT_RT enabled kernel.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.228481202@linutronix.de
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seqlock consists of a sequence counter and a spinlock_t which is used to
serialize the writers. spinlock_t is substituted by a "sleeping" spinlock
on PREEMPT_RT enabled kernels which breaks the usage in the timekeeping
code as the writers are executed in hard interrupt and therefore
non-preemptible context even on PREEMPT_RT.
The spinlock in seqlock cannot be unconditionally replaced by a
raw_spinlock_t as many seqlock users have nesting spinlock sections or
other code which is not suitable to run in truly atomic context on RT.
Instead of providing a raw_seqlock API for a single use case, open code the
seqlock for the jiffies use case and implement it with a raw_spinlock_t and
a sequence counter.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.120587764@linutronix.de
|
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The kernel provides a variety of locking primitives. The nesting of these
lock types and the implications of them on RT enabled kernels is nowhere
documented.
Add initial documentation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.026561244@linutronix.de
|
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The PS3 notification interrupt and kthread use a hacked up completion to
communicate. Since we're wanting to change the completion implementation and
this is abuse anyway, replace it with a simple rcuwait since there is only ever
the one waiter.
AFAICT the kthread uses TASK_INTERRUPTIBLE to not increase loadavg, kthreads
cannot receive signals by default and this one doesn't look different. Use
TASK_IDLE instead.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113241.930037873@linutronix.de
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Extend rcuwait_wait_event() with a state variable so that it is not
restricted to UNINTERRUPTIBLE waits.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113241.824030968@linutronix.de
|
|
The defconfig compiles without linux/mm.h. With mm.h included the
include chain leands to:
| CC kernel/locking/percpu-rwsem.o
| In file included from include/linux/huge_mm.h:8,
| from include/linux/mm.h:567,
| from arch/microblaze/include/asm/uaccess.h:,
| from include/linux/uaccess.h:11,
| from include/linux/sched/task.h:11,
| from include/linux/sched/signal.h:9,
| from include/linux/rcuwait.h:6,
| from include/linux/percpu-rwsem.h:8,
| from kernel/locking/percpu-rwsem.c:6:
| include/linux/fs.h:1422:29: error: array type has incomplete element type 'struct percpu_rw_semaphore'
| 1422 | struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS];
once rcuwait.h includes linux/sched/signal.h.
Remove the linux/mm.h include.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113241.719022171@linutronix.de
|
|
The defconfig compiles without linux/mm.h. With mm.h included the
include chain leands to:
| CC kernel/locking/percpu-rwsem.o
| In file included from include/linux/huge_mm.h:8,
| from include/linux/mm.h:567,
| from arch/ia64/include/asm/uaccess.h:,
| from include/linux/uaccess.h:11,
| from include/linux/sched/task.h:11,
| from include/linux/sched/signal.h:9,
| from include/linux/rcuwait.h:6,
| from include/linux/percpu-rwsem.h:8,
| from kernel/locking/percpu-rwsem.c:6:
| include/linux/fs.h:1422:29: error: array type has incomplete element type 'struct percpu_rw_semaphore'
| 1422 | struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS];
once rcuwait.h includes linux/sched/signal.h.
Remove the linux/mm.h include.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113241.624070289@linutronix.de
|
|
The defconfig compiles without linux/mm.h. With mm.h included the
include chain leands to:
| CC kernel/locking/percpu-rwsem.o
| In file included from include/linux/huge_mm.h:8,
| from include/linux/mm.h:567,
| from arch/hexagon/include/asm/uaccess.h:,
| from include/linux/uaccess.h:11,
| from include/linux/sched/task.h:11,
| from include/linux/sched/signal.h:9,
| from include/linux/rcuwait.h:6,
| from include/linux/percpu-rwsem.h:8,
| from kernel/locking/percpu-rwsem.c:6:
| include/linux/fs.h:1422:29: error: array type has incomplete element type 'struct percpu_rw_semaphore'
| 1422 | struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS];
once rcuwait.h includes linux/sched/signal.h.
Remove the linux/mm.h include.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113241.531525286@linutronix.de
|
|
The defconfig compiles without linux/mm.h. With mm.h included the
include chain leands to:
| CC kernel/locking/percpu-rwsem.o
| In file included from include/linux/huge_mm.h:8,
| from include/linux/mm.h:567,
| from arch/csky/include/asm/uaccess.h:,
| from include/linux/uaccess.h:11,
| from include/linux/sched/task.h:11,
| from include/linux/sched/signal.h:9,
| from include/linux/rcuwait.h:6,
| from include/linux/percpu-rwsem.h:8,
| from kernel/locking/percpu-rwsem.c:6:
| include/linux/fs.h:1422:29: error: array type has incomplete element type 'struct percpu_rw_semaphore'
| 1422 | struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS];
once rcuwait.h includes linux/sched/signal.h.
Remove the linux/mm.h include.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113241.434999165@linutronix.de
|
|
The defconfig compiles without linux/mm.h. With mm.h included the
include chain leands to:
| CC kernel/locking/percpu-rwsem.o
| In file included from include/linux/huge_mm.h:8,
| from include/linux/mm.h:567,
| from arch/nds32/include/asm/uaccess.h:,
| from include/linux/uaccess.h:11,
| from include/linux/sched/task.h:11,
| from include/linux/sched/signal.h:9,
| from include/linux/rcuwait.h:6,
| from include/linux/percpu-rwsem.h:8,
| from kernel/locking/percpu-rwsem.c:6:
| include/linux/fs.h:1422:29: error: array type has incomplete element type 'struct percpu_rw_semaphore'
| 1422 | struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS];
once rcuwait.h includes linux/sched/signal.h.
Remove the linux/mm.h include.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113241.339289758@linutronix.de
|
|
In order to avoid future header hell, remove the inclusion of
proc_fs.h from acpi_bus.h. All it needs is a forward declaration of a
struct.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lkml.kernel.org/r/20200321113241.246190285@linutronix.de
|
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The completion usage in this driver is interesting:
- it uses a magic complete function which according to the comment was
implemented by invoking complete() four times in a row because
complete_all() was not exported at that time.
- it uses an open coded wait/poll which checks completion:done. Only one wait
side (device removal) uses the regular wait_for_completion() interface.
The rationale behind this is to prevent that wait_for_completion() consumes
completion::done which would prevent that all waiters are woken. This is not
necessary with complete_all() as that sets completion::done to UINT_MAX which
is left unmodified by the woken waiters.
Replace the magic complete function with complete_all() and convert the
open coded wait/poll to regular completion interfaces.
This changes the wait to exclusive wait mode. But that does not make any
difference because the wakers use complete_all() which ignores the
exclusive mode.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lkml.kernel.org/r/20200321113241.150783464@linutronix.de
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ep_io() uses a completion on stack and open codes the waiting with:
wait_event_interruptible (done.wait, done.done);
and
wait_event (done.wait, done.done);
This waits in non-exclusive mode for complete(), but there is no reason to
do so because the completion can only be waited for by the task itself and
complete() wakes exactly one exlusive waiter.
Replace the open coded implementation with the corresponding
wait_for_completion*() functions.
No functional change.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lkml.kernel.org/r/20200321113241.043380271@linutronix.de
|
|
The poll callback is using the completion wait queue and sticks it into
poll_wait() to wake up pollers after a command has completed.
This works to some extent, but cannot provide EPOLLEXCLUSIVE support
because the waker side uses complete_all() which unconditionally wakes up
all waiters. complete_all() is required because completions internally use
exclusive wait and complete() only wakes up one waiter by default.
This mixes conceptually different mechanisms and relies on internal
implementation details of completions, which in turn puts contraints on
changing the internal implementation of completions.
Replace it with a regular wait queue and store the state in struct
switchtec_user.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113240.936097534@linutronix.de
|
