Remove unneeded blank line before a close brace '}'.
Issue found by checkpatch.pl:
CHECK: Blank lines aren't necessary before a close brace '}'
Signed-off-by: Simran Singhal <singhalsimran0@gmail.com>
Link: https://lore.kernel.org/r/20200325182617.GA9411@simran-Inspiron-5558
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add space around operators for improving the code
readability.
Reported by checkpatch.pl
git diff -w shows no difference.
diff of the .o files before and after the changes shows no difference.
Signed-off-by: Shreeya Patel <shreeya.patel23498@gmail.com>
Link: https://lore.kernel.org/r/20200325160142.3698-1-shreeya.patel23498@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Replace kzalloc(sizeof(...) * n, ...) with
kcalloc(n, sizeof(...), ...) since kcalloc is the
preferred API in case of allocating with multiply.
Checkpatch.pl: WARNING:
Prefer kcalloc over kzalloc with multiply.
Signed-off-by: Sam Muhammed <jane.pnx9@gmail.com>
Link: https://lore.kernel.org/r/4b8339d1e81e497c3c2f0dad57a9587338ec82b1.1585143581.git.jane.pnx9@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kzalloc(sizeof(*var), ...) was the format been used
across the driver, which is the preferred format,
but missed two instances, correct them to match the
coding standards.
Checkpatch.pl CHECK: Prefer kzalloc(sizeof(*var)...)
over kzalloc(sizeof(struct var)...)
Signed-off-by: Sam Muhammed <jane.pnx9@gmail.com>
Link: https://lore.kernel.org/r/bbb3adbd20ae89db6a0d3360bc09d22eed778e86.1585143581.git.jane.pnx9@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Shift the end of multiline comments "*/" to the next line and align the
lines of the comments properly to improve code readability and to adhere
to the Linux Kernel coding style.
Reported by checkpatch.pl
Signed-off-by: Soumyajit Deb <debsoumyajit100@gmail.com>
Link: https://lore.kernel.org/r/20200325180003.46749-1-debsoumyajit100@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add whiteline after variable declarations to remove the checkpatch.pl
warning:
WARNING: Missing a blank line after declarations
Signed-off-by: Simran Singhal <singhalsimran0@gmail.com>
Link: https://lore.kernel.org/r/20200325164451.GA17569@simran-Inspiron-5558
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add space around "-" operator to improve code readability and adhere to
the Linux kernel coding style.
Reported by checkpatch.pl
Signed-off-by: Soumyajit Deb <debsoumyajit100@gmail.com>
Link: https://lore.kernel.org/r/20200325144353.42655-1-debsoumyajit100@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Remove multiple assignments by factorizing them.
Problem found using checkpatch.pl:-
CHECK: multiple assignments should be avoided
Signed-off-by: Simran Singhal <singhalsimran0@gmail.com>
Link: https://lore.kernel.org/r/20200325142226.GA14711@simran-Inspiron-5558
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Clean up unnecessary braces around single statement blocks.
Issues reported by checkpatch.pl as:
WARNING: braces {} are not necessary for single statement blocks
Signed-off-by: Simran Singhal <singhalsimran0@gmail.com>
Link: https://lore.kernel.org/r/20200325140245.GA11949@simran-Inspiron-5558
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add space between if and open parenthesis to improve
code readability and to adhere to the standard linux kernel
coding style. Also, shift the next line to the right by a single space
as it is the continuation of the above if statement.
Signed-off-by: Soumyajit Deb <debsoumyajit100@gmail.com>
Link: https://lore.kernel.org/r/20200325122752.38600-1-debsoumyajit100@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add space between while keyword and open parenthesis "(" in the do while
statement to improve code readability and to adhere to the Linux Kernel
coding style.
Reported by checkpatch.pl
Signed-off-by: Soumyajit Deb <debsoumyajit100@gmail.com>
Link: https://lore.kernel.org/r/20200325115956.37126-1-debsoumyajit100@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Remove space after opening parenthesis in if statement to improve code
readability and to adhere to the standard coding style.
Reported by checkpatch.pl
Signed-off-by: Soumyajit Deb <debsoumyajit100@gmail.com>
Link: https://lore.kernel.org/r/20200325072905.29066-7-debsoumyajit100@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add space after "," in function arguments to improve code readability.
Reported by checkpatch.pl
Signed-off-by: Soumyajit Deb <debsoumyajit100@gmail.com>
Link: https://lore.kernel.org/r/20200325072905.29066-6-debsoumyajit100@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Update matches style found elsewhere in file.
Issue found by checkpatch: line over 80 characters.
Signed-off-by: Briana Oursler <briana.oursler@gmail.com>
Link: https://lore.kernel.org/r/20200324183812.79411-1-briana.oursler@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
void (*read_buff_add) argument didn't have an identifier name,
adding a name to it like the rest of all functions' arguments.
Signed-off-by: Sam Muhammed <jane.pnx9@gmail.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Link: https://lore.kernel.org/r/b2a1ca962553194840d8cd2bf1f7d3174e3b1336.1585046066.git.jane.pnx9@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Modifying struct allocation in kmalloc() to match the
coding standards.
Checkpatch.pl CHECK: Prefer kmalloc(sizeof(*ldisc_data)...)
over kmalloc(sizeof(struct spk_ldisc_data)...)
Signed-off-by: Sam Muhammed <jane.pnx9@gmail.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Link: https://lore.kernel.org/r/19494bdab5709693126e0c0ee14b179a3b601207.1585046066.git.jane.pnx9@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reformat multi-line dereferencing of function arguments
&cmd->scan_begin_arg. Also reformat another call to the same function to
follow the same argument formatting structure. Problem detected by
checkpatch script.
Signed-off-by: Deepak R Varma <mh12gx2825@gmail.com>
Link: https://lore.kernel.org/r/20200322185932.GA12594@deeUbuntu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Checkpatch would flash a check message around a stringified macro
argument containing a '-' character. Add comment to indicate the
argument is legitimate and doesn't need fixing.
Signed-off-by: Deepak R Varma <mh12gx2825@gmail.com>
Suggested-by: Lars-Peter Clausen <lars@metafoo.de>
Link: https://lore.kernel.org/r/469bf8db1c228913e72841367182fba2168fe795.1584904896.git.mh12gx2825@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Create a new 'status' variable to store the value of a long argument
that goes over 80 characters. The status variable is also used for
an if check. Replacing that long statement in both places makes the
code much easier to read.
Note: the status variable is assigned after a needed byte order
conversion for usbin->rxfrm.desc.status, which uses a reference.
Issue reported by checkpatch.
Suggested-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: John B. Wyatt IV <jbwyatt4@gmail.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Link: https://lore.kernel.org/r/20200321225808.2494564-1-jbwyatt4@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Dropping a user-defined pr_warn() and using the kernel
message printing functions implemented in <linux/printk.h>.
Since both have the same functionality, using the standard
kernel functions is better.
Signed-off-by: Sam Muhammed <jane.pnx9@gmail.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Link: https://lore.kernel.org/r/20200322143322.29098-1-jane.pnx9@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch fixes the check reported by checkpatch.pl
for braces {} should be used on all arms of this statement.
Signed-off-by: Simran Singhal <singhalsimran0@gmail.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20200322173045.GA24700@simran-Inspiron-5558
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Setting up kernel resource 'iomem_resource' for PCI with
addresses parsed from device tree gots into a conflict within
the usb xhci driver:
xhci-mtk 1e1c0000.xhci: can't request region for resource [mem 0x1e1c0000-0x1e1c0fff]
xhci-mtk: probe of 1e1c0000.xhci failed with error -16
Don't assign it and maintain the default addresses for this
resource seems to fix the problem. Checking legacy driver it
is being only setting the 'ioport_resource'.
Fixes: 09dd629eea ("staging: mt7621-pci: fix io space and properly set resource limits")
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20200322072128.4454-1-sergio.paracuellos@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Remove space after * in pointer declaration to improve code readability
and to adhere to the standard coding style.
Reported by checkpatch.pl
Signed-off-by: Soumyajit Deb <debsoumyajit100@gmail.com>
Link: https://lore.kernel.org/r/20200323054836.48816-3-debsoumyajit100@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This replaces printk(KERN_WARNING ..) with netdev_warn(),
as the use of printk() isn't preferred when
a struct net_device is available.
Signed-off-by: Sam Muhammed <jane.pnx9@gmail.com>
Acked-by: Julia Lawall <julia.lawall@inria.fr>
Link: https://lore.kernel.org/r/20200322115051.2767-1-jane.pnx9@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The ASUS USB-N10 Nano B1 has been reported as a new RTL8188EU device.
Add it to the device tables.
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Reported-by: kovi <zraetn@gmail.com>
Cc: Stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200321180011.26153-1-Larry.Finger@lwfinger.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Detection of the Xtal mode is using magic numbers that
can be avoided using properly some definitions and a more
accurate variable name from 'reg' into 'xtal_mode'. This
increase readability.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20200321133624.31388-4-sergio.paracuellos@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Macro builtin_platform_driver can be used for builtin drivers
that don't do anything in driver init. So, use the macro
builtin_platform_driver and remove some boilerplate code.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20200321133624.31388-3-sergio.paracuellos@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Macro builtin_platform_driver can be used for builtin drivers
that don't do anything in driver init. So, use the macro
builtin_platform_driver and remove some boilerplate code.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20200321133624.31388-1-sergio.paracuellos@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'for-5.6-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"Two fixes.
The first is a regression: when dropping some incompat bits the
conditions were reversed. The other is a fix for rename whiteout
potentially leaving stack memory linked to a list"
* tag 'for-5.6-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: fix removal of raid[56|1c34} incompat flags after removing block group
btrfs: fix log context list corruption after rename whiteout error
Merge misc fixes from Andrew Morton:
"10 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
x86/mm: split vmalloc_sync_all()
mm, slub: prevent kmalloc_node crashes and memory leaks
mm/mmu_notifier: silence PROVE_RCU_LIST warnings
epoll: fix possible lost wakeup on epoll_ctl() path
mm: do not allow MADV_PAGEOUT for CoW pages
mm, memcg: throttle allocators based on ancestral memory.high
mm, memcg: fix corruption on 64-bit divisor in memory.high throttling
page-flags: fix a crash at SetPageError(THP_SWAP)
mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case
memcg: fix NULL pointer dereference in __mem_cgroup_usage_unregister_event
Commit 3f8fd02b1b ("mm/vmalloc: Sync unmappings in
__purge_vmap_area_lazy()") introduced a call to vmalloc_sync_all() in
the vunmap() code-path. While this change was necessary to maintain
correctness on x86-32-pae kernels, it also adds additional cycles for
architectures that don't need it.
Specifically on x86-64 with CONFIG_VMAP_STACK=y some people reported
severe performance regressions in micro-benchmarks because it now also
calls the x86-64 implementation of vmalloc_sync_all() on vunmap(). But
the vmalloc_sync_all() implementation on x86-64 is only needed for newly
created mappings.
To avoid the unnecessary work on x86-64 and to gain the performance
back, split up vmalloc_sync_all() into two functions:
* vmalloc_sync_mappings(), and
* vmalloc_sync_unmappings()
Most call-sites to vmalloc_sync_all() only care about new mappings being
synchronized. The only exception is the new call-site added in the
above mentioned commit.
Shile Zhang directed us to a report of an 80% regression in reaim
throughput.
Fixes: 3f8fd02b1b ("mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()")
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Shile Zhang <shile.zhang@linux.alibaba.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Borislav Petkov <bp@suse.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> [GHES]
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20191009124418.8286-1-joro@8bytes.org
Link: https://lists.01.org/hyperkitty/list/lkp@lists.01.org/thread/4D3JPPHBNOSPFK2KEPC6KGKS6J25AIDB/
Link: http://lkml.kernel.org/r/20191113095530.228959-1-shile.zhang@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sachin reports [1] a crash in SLUB __slab_alloc():
BUG: Kernel NULL pointer dereference on read at 0x000073b0
Faulting instruction address: 0xc0000000003d55f4
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in:
CPU: 19 PID: 1 Comm: systemd Not tainted 5.6.0-rc2-next-20200218-autotest #1
NIP: c0000000003d55f4 LR: c0000000003d5b94 CTR: 0000000000000000
REGS: c0000008b37836d0 TRAP: 0300 Not tainted (5.6.0-rc2-next-20200218-autotest)
MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 24004844 XER: 00000000
CFAR: c00000000000dec4 DAR: 00000000000073b0 DSISR: 40000000 IRQMASK: 1
GPR00: c0000000003d5b94 c0000008b3783960 c00000000155d400 c0000008b301f500
GPR04: 0000000000000dc0 0000000000000002 c0000000003443d8 c0000008bb398620
GPR08: 00000008ba2f0000 0000000000000001 0000000000000000 0000000000000000
GPR12: 0000000024004844 c00000001ec52a00 0000000000000000 0000000000000000
GPR16: c0000008a1b20048 c000000001595898 c000000001750c18 0000000000000002
GPR20: c000000001750c28 c000000001624470 0000000fffffffe0 5deadbeef0000122
GPR24: 0000000000000001 0000000000000dc0 0000000000000002 c0000000003443d8
GPR28: c0000008b301f500 c0000008bb398620 0000000000000000 c00c000002287180
NIP ___slab_alloc+0x1f4/0x760
LR __slab_alloc+0x34/0x60
Call Trace:
___slab_alloc+0x334/0x760 (unreliable)
__slab_alloc+0x34/0x60
__kmalloc_node+0x110/0x490
kvmalloc_node+0x58/0x110
mem_cgroup_css_online+0x108/0x270
online_css+0x48/0xd0
cgroup_apply_control_enable+0x2ec/0x4d0
cgroup_mkdir+0x228/0x5f0
kernfs_iop_mkdir+0x90/0xf0
vfs_mkdir+0x110/0x230
do_mkdirat+0xb0/0x1a0
system_call+0x5c/0x68
This is a PowerPC platform with following NUMA topology:
available: 2 nodes (0-1)
node 0 cpus:
node 0 size: 0 MB
node 0 free: 0 MB
node 1 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
node 1 size: 35247 MB
node 1 free: 30907 MB
node distances:
node 0 1
0: 10 40
1: 40 10
possible numa nodes: 0-31
This only happens with a mmotm patch "mm/memcontrol.c: allocate
shrinker_map on appropriate NUMA node" [2] which effectively calls
kmalloc_node for each possible node. SLUB however only allocates
kmem_cache_node on online N_NORMAL_MEMORY nodes, and relies on
node_to_mem_node to return such valid node for other nodes since commit
a561ce00b0 ("slub: fall back to node_to_mem_node() node if allocating
on memoryless node"). This is however not true in this configuration
where the _node_numa_mem_ array is not initialized for nodes 0 and 2-31,
thus it contains zeroes and get_partial() ends up accessing
non-allocated kmem_cache_node.
A related issue was reported by Bharata (originally by Ramachandran) [3]
where a similar PowerPC configuration, but with mainline kernel without
patch [2] ends up allocating large amounts of pages by kmalloc-1k
kmalloc-512. This seems to have the same underlying issue with
node_to_mem_node() not behaving as expected, and might probably also
lead to an infinite loop with CONFIG_SLUB_CPU_PARTIAL [4].
This patch should fix both issues by not relying on node_to_mem_node()
anymore and instead simply falling back to NUMA_NO_NODE, when
kmalloc_node(node) is attempted for a node that's not online, or has no
usable memory. The "usable memory" condition is also changed from
node_present_pages() to N_NORMAL_MEMORY node state, as that is exactly
the condition that SLUB uses to allocate kmem_cache_node structures.
The check in get_partial() is removed completely, as the checks in
___slab_alloc() are now sufficient to prevent get_partial() being
reached with an invalid node.
[1] https://lore.kernel.org/linux-next/3381CD91-AB3D-4773-BA04-E7A072A63968@linux.vnet.ibm.com/
[2] https://lore.kernel.org/linux-mm/fff0e636-4c36-ed10-281c-8cdb0687c839@virtuozzo.com/
[3] https://lore.kernel.org/linux-mm/20200317092624.GB22538@in.ibm.com/
[4] https://lore.kernel.org/linux-mm/088b5996-faae-8a56-ef9c-5b567125ae54@suse.cz/
Fixes: a561ce00b0 ("slub: fall back to node_to_mem_node() node if allocating on memoryless node")
Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Reported-by: PUVICHAKRAVARTHY RAMACHANDRAN <puvichakravarthy@in.ibm.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Tested-by: Bharata B Rao <bharata@linux.ibm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Christopher Lameter <cl@linux.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200320115533.9604-1-vbabka@suse.cz
Debugged-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is safe to traverse mm->notifier_subscriptions->list either under
SRCU read lock or mm->notifier_subscriptions->lock using
hlist_for_each_entry_rcu(). Silence the PROVE_RCU_LIST false positives,
for example,
WARNING: suspicious RCU usage
-----------------------------
mm/mmu_notifier.c:484 RCU-list traversed in non-reader section!!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
3 locks held by libvirtd/802:
#0: ffff9321e3f58148 (&mm->mmap_sem#2){++++}, at: do_mprotect_pkey+0xe1/0x3e0
#1: ffffffff91ae6160 (mmu_notifier_invalidate_range_start){+.+.}, at: change_p4d_range+0x5fa/0x800
#2: ffffffff91ae6e08 (srcu){....}, at: __mmu_notifier_invalidate_range_start+0x178/0x460
stack backtrace:
CPU: 7 PID: 802 Comm: libvirtd Tainted: G I 5.6.0-rc6-next-20200317+ #2
Hardware name: HP ProLiant BL460c Gen8, BIOS I31 11/02/2014
Call Trace:
dump_stack+0xa4/0xfe
lockdep_rcu_suspicious+0xeb/0xf5
__mmu_notifier_invalidate_range_start+0x3ff/0x460
change_p4d_range+0x746/0x800
change_protection+0x1df/0x300
mprotect_fixup+0x245/0x3e0
do_mprotect_pkey+0x23b/0x3e0
__x64_sys_mprotect+0x51/0x70
do_syscall_64+0x91/0xae8
entry_SYSCALL_64_after_hwframe+0x49/0xb3
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Link: http://lkml.kernel.org/r/20200317175640.2047-1-cai@lca.pw
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This fixes possible lost wakeup introduced by commit a218cc4914.
Originally modifications to ep->wq were serialized by ep->wq.lock, but
in commit a218cc4914 ("epoll: use rwlock in order to reduce
ep_poll_callback() contention") a new rw lock was introduced in order to
relax fd event path, i.e. callers of ep_poll_callback() function.
After the change ep_modify and ep_insert (both are called on epoll_ctl()
path) were switched to ep->lock, but ep_poll (epoll_wait) was using
ep->wq.lock on wqueue list modification.
The bug doesn't lead to any wqueue list corruptions, because wake up
path and list modifications were serialized by ep->wq.lock internally,
but actual waitqueue_active() check prior wake_up() call can be
reordered with modifications of ep ready list, thus wake up can be lost.
And yes, can be healed by explicit smp_mb():
list_add_tail(&epi->rdlink, &ep->rdllist);
smp_mb();
if (waitqueue_active(&ep->wq))
wake_up(&ep->wp);
But let's make it simple, thus current patch replaces ep->wq.lock with
the ep->lock for wqueue modifications, thus wake up path always observes
activeness of the wqueue correcty.
Fixes: a218cc4914 ("epoll: use rwlock in order to reduce ep_poll_callback() contention")
Reported-by: Max Neunhoeffer <max@arangodb.com>
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Max Neunhoeffer <max@arangodb.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Christopher Kohlhoff <chris.kohlhoff@clearpool.io>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jes Sorensen <jes.sorensen@gmail.com>
Cc: <stable@vger.kernel.org> [5.1+]
Link: http://lkml.kernel.org/r/20200214170211.561524-1-rpenyaev@suse.de
References: https://bugzilla.kernel.org/show_bug.cgi?id=205933
Bisected-by: Max Neunhoeffer <max@arangodb.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jann has brought up a very interesting point [1]. While shared pages
are excluded from MADV_PAGEOUT normally, CoW pages can be easily
reclaimed that way. This can lead to all sorts of hard to debug
problems. E.g. performance problems outlined by Daniel [2].
There are runtime environments where there is a substantial memory
shared among security domains via CoW memory and a easy to reclaim way
of that memory, which MADV_{COLD,PAGEOUT} offers, can lead to either
performance degradation in for the parent process which might be more
privileged or even open side channel attacks.
The feasibility of the latter is not really clear to me TBH but there is
no real reason for exposure at this stage. It seems there is no real
use case to depend on reclaiming CoW memory via madvise at this stage so
it is much easier to simply disallow it and this is what this patch
does. Put it simply MADV_{PAGEOUT,COLD} can operate only on the
exclusively owned memory which is a straightforward semantic.
[1] http://lkml.kernel.org/r/CAG48ez0G3JkMq61gUmyQAaCq=_TwHbi1XKzWRooxZkv08PQKuw@mail.gmail.com
[2] http://lkml.kernel.org/r/CAKOZueua_v8jHCpmEtTB6f3i9e2YnmX4mqdYVWhV4E=Z-n+zRQ@mail.gmail.com
Fixes: 9c276cc65a ("mm: introduce MADV_COLD")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Daniel Colascione <dancol@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200312082248.GS23944@dhcp22.suse.cz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
