github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-10 07:32:29 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph
b035bb9573
linux/arch/sparc/kernel
History
Nicholas Piggin 4775def575 sparc64: remove mm_cpumask clearing to fix kthread_use_mm race 
[ Upstream commit bafb056ce2 ]

The de facto (and apparently uncommented) standard for using an mm had,
thanks to this code in sparc if nothing else, been that you must have a
reference on mm_users *and that reference must have been obtained with
mmget()*, i.e., from a thread with a reference to mm_users that had used
the mm.

The introduction of mmget_not_zero() in commit d2005e3f41
("userfaultfd: don't pin the user memory in userfaultfd_file_create()")
allowed mm_count holders to aoperate on user mappings asynchronously
from the actual threads using the mm, but they were not to load those
mappings into their TLB (i.e., walking vmas and page tables is okay,
kthread_use_mm() is not).

io_uring 2b188cc1bb ("Add io_uring IO interface") added code which
does a kthread_use_mm() from a mmget_not_zero() refcount.

The problem with this is code which previously assumed mm == current->mm
and mm->mm_users == 1 implies the mm will remain single-threaded at
least until this thread creates another mm_users reference, has now
broken.

arch/sparc/kernel/smp_64.c:

    if (atomic_read(&mm->mm_users) == 1) {
        cpumask_copy(mm_cpumask(mm), cpumask_of(cpu));
        goto local_flush_and_out;
    }

vs fs/io_uring.c

    if (unlikely(!(ctx->flags & IORING_SETUP_SQPOLL) ||
                 !mmget_not_zero(ctx->sqo_mm)))
        return -EFAULT;
    kthread_use_mm(ctx->sqo_mm);

mmget_not_zero() could come in right after the mm_users == 1 test, then
kthread_use_mm() which sets its CPU in the mm_cpumask. That update could
be lost if cpumask_copy() occurs afterward.

I propose we fix this by allowing mmget_not_zero() to be a first-class
reference, and not have this obscure undocumented and unchecked
restriction.

The basic fix for sparc64 is to remove its mm_cpumask clearing code. The
optimisation could be effectively restored by sending IPIs to mm_cpumask
members and having them remove themselves from mm_cpumask. This is more
tricky so I leave it as an exercise for someone with a sparc64 SMP.
powerpc has a (currently similarly broken) example.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914045219.3736466-4-npiggin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-11-05 11:08:38 +01:00
..
.gitignore
adi_64.c sparc64: Add support for ADI (Application Data Integrity) 2018-03-18 07:38:48 -07:00
apc.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
asm-offsets.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
audit.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
auxio_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
auxio_64.c Revert "sparc: Convert to using %pOFn instead of device_node.name" 2018-10-15 18:32:54 -07:00
btext.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
central.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cherrs.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
chmc.c sparc: kernel: drop owner assignment from platform_drivers 2014-10-20 16:20:15 +02:00
compat_audit.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cpu.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cpumap.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cpumap.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
devices.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ds.c sparc64: Fix build warnings with gcc 7. 2017-06-01 09:42:46 -07:00
dtlb_miss.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dtlb_prot.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ebus.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
entry.h sparc64: Add support for ADI register fields, ASIs and traps 2018-03-18 07:38:45 -07:00
entry.S sparc: get rid of asm wrapper for nis_syscall() 2018-03-20 12:05:17 -04:00
etrap_32.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
etrap_64.S sparc64: Add support for ADI (Application Data Integrity) 2018-03-18 07:38:48 -07:00
fpu_traps.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ftrace.c sparc/function_graph: Simplify with function_graph_enter() 2018-12-05 19:32:10 +01:00
getsetcc.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
head_32.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
head_64.S sparc64: Add support for ADI register fields, ASIs and traps 2018-03-18 07:38:45 -07:00
helpers.S sparc: move exports to definitions 2016-08-07 23:55:43 -04:00
hvapi.c sparc64: Oracle DAX infrastructure 2018-01-22 08:17:15 -08:00
hvcalls.S sparc64: Oracle DAX infrastructure 2018-01-22 08:17:15 -08:00
hvtramp.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
idprom.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
iommu_common.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
iommu-common.c iommu-common: move to arch/sparc 2018-05-09 06:54:27 +02:00
iommu.c iommu-common: move to arch/sparc 2018-05-09 06:54:27 +02:00
ioport.c sparc: use generic dma_noncoherent_ops 2018-08-21 12:37:16 -07:00
irq_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
irq_64.c headers: untangle kmemleak.h from mm.h 2018-04-05 21:36:27 -07:00
irq.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
itlb_miss.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ivec.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
jump_label.c jump_label: move 'asm goto' support test to Kconfig 2019-06-04 08:02:34 +02:00
kernel.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kgdb_32.c sparc32: fix fall-through annotation 2018-10-07 22:42:02 -07:00
kgdb_64.c sparc64: fix fall-through annotation 2018-10-07 22:42:02 -07:00
kprobes.c bpf/error-inject/kprobes: Clear current_kprobe and enable preempt in kprobe 2018-06-21 12:33:19 +02:00
kstack.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ktlb.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ldc.c iommu-common: move to arch/sparc 2018-05-09 06:54:27 +02:00
led.c sparc/led: Convert timers to use timer_setup() 2017-11-15 14:27:50 +09:00
leon_kernel.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
leon_pci_grpci1.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
leon_pci_grpci2.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
leon_pci.c sparc/PCI: Use dev_printk() when possible 2018-05-22 07:54:06 -05:00
leon_pmc.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
leon_smp.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile jump_label: move 'asm goto' support test to Kconfig 2019-06-04 08:02:34 +02:00
mdesc.c mdesc: fix a missing-check bug in get_vdev_port_node_info() 2019-06-25 11:35:57 +08:00
misctrap.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
module.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
nmi.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
of_device_32.c sparc: set a default 32-bit dma mask for OF devices 2018-09-02 10:02:04 +02:00
of_device_64.c sparc: set a default 32-bit dma mask for OF devices 2018-09-02 10:02:04 +02:00
of_device_common.c sparc: fix sparse warnings in of_device_common.c 2014-04-29 01:12:27 -04:00
of_device_common.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci_common.c sparc/PCI: Use dev_printk() when possible 2018-05-22 07:54:06 -05:00
pci_fire.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci_impl.h sparc/PCI: Support arbitrary host bridge address offset 2018-02-15 15:07:30 -06:00
pci_msi.c sparc/PCI: Use dev_printk() when possible 2018-05-22 07:54:06 -05:00
pci_psycho.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci_sabre.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci_schizo.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci_sun4v_asm.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci_sun4v.c iommu-common: move to arch/sparc 2018-05-09 06:54:27 +02:00
pci_sun4v.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci.c sparc/PCI: Use dev_printk() when possible 2018-05-22 07:54:06 -05:00
pcic.c sparc/PCI: Use dev_printk() when possible 2018-05-22 07:54:06 -05:00
pcr.c sparc: perf: Add support M7 processor 2015-03-19 18:54:49 -07:00
perf_event.c sparc: perf: fix updated event period in response to PERF_EVENT_IOC_PERIOD 2019-06-25 11:35:57 +08:00
pmc.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
power.c Revert "sparc: Convert to using %pOFn instead of device_node.name" 2018-10-15 18:32:54 -07:00
process_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
process_64.c sparc64: Make corrupted user stacks more debuggable. 2018-11-04 14:50:54 +01:00
prom_32.c Revert "sparc: Convert to using %pOFn instead of device_node.name" 2018-10-15 18:32:54 -07:00
prom_64.c Revert "sparc: Convert to using %pOFn instead of device_node.name" 2018-10-15 18:32:54 -07:00
prom_common.c
prom_irqtrans.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
prom.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
psycho_common.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
psycho_common.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ptrace_32.c fix a braino in "sparc32: fix register window handling in genregs32_[gs]et()" 2020-06-30 23:17:02 -04:00
ptrace_64.c sparc64: fix misuses of access_process_vm() in genregs32_[sg]et() 2020-06-22 09:05:28 +02:00
reboot.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rtrap_32.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rtrap_64.S sparc64: Make corrupted user stacks more debuggable. 2018-11-04 14:50:54 +01:00
sbus.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
setup_32.c fs: add ksys_sync() helper; remove in-kernel calls to sys_sync() 2018-04-02 20:16:05 +02:00
setup_64.c sparc64: Add support for ADI (Application Data Integrity) 2018-03-18 07:38:48 -07:00
signal_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
signal_64.c sparc64: Make corrupted user stacks more debuggable. 2018-11-04 14:50:54 +01:00
signal32.c sparc64: Make corrupted user stacks more debuggable. 2018-11-04 14:50:54 +01:00
sigutil_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sigutil_64.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sigutil.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
smp_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
smp_64.c sparc64: remove mm_cpumask clearing to fix kthread_use_mm race 2020-11-05 11:08:38 +01:00
sparc_ksyms.c sparc: move exports to definitions 2016-08-07 23:55:43 -04:00
spiterrs.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sstate.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
stacktrace.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
starfire.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sun4d_irq.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sun4d_smp.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sun4m_irq.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sun4m_smp.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sun4v_ivec.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sun4v_mcd.S sparc64: Add support for ADI register fields, ASIs and traps 2018-03-18 07:38:45 -07:00
sun4v_tlb_miss.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sys_sparc_32.c sys: don't hold uts_sem while accessing userspace memory 2018-08-11 02:05:53 -05:00
sys_sparc_64.c sys: don't hold uts_sem while accessing userspace memory 2018-08-11 02:05:53 -05:00
sys_sparc32.c Merge branch 'misc.sparc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-04-07 14:30:28 -07:00
sys32.S sparc: get rid of remaining SIGN... wrappers 2018-03-20 12:01:23 -04:00
syscalls.S sparc: get rid of asm wrapper for nis_syscall() 2018-03-20 12:05:17 -04:00
sysfs.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
systbls_32.S sparc: Wire up io_pgetevents system call. 2018-10-09 16:52:38 -07:00
systbls_64.S sparc64: Wire up compat getpeername and getsockname. 2018-11-04 14:50:54 +01:00
systbls.h sparc: get rid of asm wrapper for nis_syscall() 2018-03-20 12:05:17 -04:00
time_32.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
time_64.c sparc/time: Add missing __init to init_tick_ops() 2018-07-30 12:48:29 -07:00
trampoline_32.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trampoline_64.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
traps_32.c signal/sparc: Use force_sig_fault where appropriate 2018-04-25 10:44:10 -05:00
traps_64.c signal/sparc: Use force_sig_fault where appropriate 2018-04-25 10:44:10 -05:00
tsb.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ttable_32.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ttable_64.S sparc64: Add support for ADI register fields, ASIs and traps 2018-03-18 07:38:45 -07:00
una_asm_32.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
una_asm_64.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
unaligned_32.c signal/sparc: Use send_sig_fault where appropriate 2018-04-25 10:44:09 -05:00
unaligned_64.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
uprobes.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
urtt_fill.S sparc64: Add support for ADI (Application Data Integrity) 2018-03-18 07:38:48 -07:00
utrap.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vdso.c vDSO for sparc 2017-11-15 14:21:03 +09:00
vio.c sparc: vio: use put_device() instead of kfree() 2018-04-30 16:09:34 -04:00
viohs.c sparc64: viohs: Remove VLA usage 2018-10-07 22:42:00 -07:00
visemul.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vmlinux.lds.S sparc: Add .exit.data section. 2020-02-24 08:34:37 +01:00
windows.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
winfixup.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
wof.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
wuf.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00