Wei Wang says:
====================
remove dst garbage collector logic
The current mechanism of dst release is a bit complicated. It is because
the users of dst get divided into 2 situations:
1. Most users take the reference count when using a dst and release the
reference count when done.
2. Exceptional users like IPv4/IPv6/decnet/xfrm routing code do not take
reference count when referencing to a dst due to some histotic reasons.
Due to those exceptional use cases in 2, reference count being 0 is not an
adequate evidence to indicate that no user is using this dst. So users in 1
can't free the dst simply based on reference count being 0 because users in
2 might still hold reference to it.
Instead, a dst garbage list is needed to hold the dst entries that already
get removed by the users in 2 but are still held by users in 1. And a periodic
garbage collector task is run to check all the dst entries in the list to see
if the users in 1 have released the reference to those dst entries.
If so, the dst is now ready to be freed.
This logic introduces unnecessary complications in the dst code which makes it
hard to understand and to debug.
In order to get rid of the whole dst garbage collector (gc) and make the dst
code more unified and simplified, we can make the users in 2 also take reference
count on the dst and release it properly when done.
This way, dst can be safely freed once the refcount drops to 0 and no gc
thread is needed anymore.
This patch series' target is to completely get rid of dst gc logic and free
dst based on reference count only.
Patch 1-3 are preparation patches to do some cleanup/improvement on the existing
code to make later work easier.
Patch 4-21 are real implementations.
In these patches, a temporary flag DST_NOGC is used to help transition
those exceptional users one by one. Once every component is transitioned,
this temporary flag is removed.
By the end of this patch series, all dst are refcounted when being used
and released when done. And dst will be freed when its refcount drops to 0.
No dst gc task is running anymore.
Note: This patch series depends on the decnet fix that was sent right before:
"decnet: always not take dst->__refcnt when inserting dst into hash table"
v2:
add curly braces in udp_v4/6_early_demux() in patch 02
add EXPORT_SYMBOL() for dst_dev_put() in patch 05
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch is meant to add a debug warning on the situation where dst is
being held during its destroy phase. This could potentially cause double
free issue on the dst.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As some dst flags are removed, reorder the dst flags to fill in the
blanks.
Note: these flags are not exposed into user space. So it is safe to
reorder.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
DST_NOCACHE flag check has been removed from dst_release() and
dst_hold_safe() in a previous patch because all the dst are now ref
counted properly and can be released based on refcnt only.
Looking at the rest of the DST_NOCACHE use, all of them can now be
removed or replaced with other checks.
So this patch gets rid of all the DST_NOCACHE usage and remove this flag
completely.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Now that all the components have been changed to release dst based on
refcnt only and not depend on dst gc anymore, we can remove the
temporary flag DST_NOGC.
Note that we also need to remove the DST_NOCACHE check in dst_release()
and dst_hold_safe() because now all the dst are released based on refcnt
and behaves as DST_NOCACHE.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch removes all dst gc related code and all the dst free
functions
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
struct dn_route is inserted into dn_rt_hash_table but no dst->__refcnt
is taken.
This patch makes sure the dn_rt_hash_table's reference to the dst is ref
counted.
As the dst is always ref counted properly, we can safely mark
DST_NOGC flag so dst_release() will release dst based on refcnt only.
And dst gc is no longer needed and all dst_free() or its related
function calls should be replaced with dst_release() or
dst_release_immediate(). And dst_dev_put() is called when removing dst
from the hash table to release the reference on dst->dev before we lose
pointer to it.
Also, correct the logic in dn_dst_check_expire() and dn_dst_gc() to
check dst->__refcnt to be > 1 to indicate it is referenced by other
users.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
During the creation of xfrm_dst bundle, always take ref count when
allocating the dst. This way, xfrm_bundle_create() will form a linked
list of dst with dst->child pointing to a ref counted dst child. And
the returned dst pointer is also ref counted. This makes the link from
the flow cache to this dst now ref counted properly.
As the dst is always ref counted properly, we can safely mark
DST_NOGC flag so dst_release() will release dst based on refcnt only.
And dst gc is no longer needed and all dst_free() and its related
function calls should be replaced with dst_release() or
dst_release_immediate().
The special handling logic for dst->child in dst_destroy() can be
replaced with a simple dst_release_immediate() call on the child to
release the whole list linked by dst->child pointer.
Previously used DST_NOHASH flag is not needed anymore as well. The
reason that DST_NOHASH is used in the existing code is mainly to prevent
the dst inserted in the fib tree to be wrongly destroyed during the
deletion of the xfrm_dst bundle. So in the existing code, DST_NOHASH
flag is marked in all the dst children except the one which is in the
fib tree.
However, with this patch series to remove dst gc logic and release dst
only based on ref count, it is safe to release all the children from a
xfrm_dst bundle as long as the dst children are all ref counted
properly which is already the case in the existing code.
So, this patch removes the use of DST_NOHASH flag.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
icmp6 dst route is currently ref counted during creation and will be
freed by user during its call of dst_release(). So no need of a garbage
collector for it.
Remove all icmp6 dst garbage collector related code.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
With the previous preparation patches, we are ready to get rid of the
dst gc operation in ipv6 code and release dst based on refcnt only.
So this patch adds DST_NOGC flag for all IPv6 dst and remove the calls
to dst_free() and its related functions.
At this point, all dst created in ipv6 code do not use the dst gc
anymore and will be destroyed at the point when refcnt drops to 0.
Also, as icmp6 dst route is refcounted during creation and will be freed
by user during its call of dst_release(), there is no need to add this
dst to the icmp6 gc list as well.
Instead, we need to add it into uncached list so that when a
NETDEV_DOWN/NETDEV_UNREGISRER event comes, we can properly go through
these icmp6 dst as well and release the net device properly.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Similar as ipv4, ipv6 path also needs to call dst_hold_safe() when
necessary to avoid double free issue on the dst.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As the intend of this patch series is to completely remove dst gc,
we need to call dst_dev_put() to release the reference to dst->dev
when removing routes from fib because we won't keep the gc list anymore
and will lose the dst pointer right after removing the routes.
Without the gc list, there is no way to find all the dst's that have
dst->dev pointing to the going-down dev.
Hence, we are doing dst_dev_put() immediately before we lose the last
reference of the dst from the routing code. The next dst_check() will
trigger a route re-lookup to find another route (if there is any).
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In IPv6 routing code, struct rt6_info is created for each static route
and RTF_CACHE route and inserted into fib6 tree. In both cases, dst
ref count is not taken.
As explained in the previous patch, this leads to the need of the dst
garbage collector.
This patch holds ref count of dst before inserting the route into fib6
tree and properly releases the dst when deleting it from the fib6 tree
as a preparation in order to fully get rid of dst gc later.
Also, correct fib6_age() logic to check dst->__refcnt to be 1 to indicate
no user is referencing the dst.
And remove dst_hold() in vrf_rt6_create() as ip6_dst_alloc() already puts
dst->__refcnt to 1.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
With the previous preparation patches, we are ready to get rid of the
dst gc operation in ipv4 code and release dst based on refcnt only.
So this patch adds DST_NOGC flag for all IPv4 dst and remove the calls
to dst_free().
At this point, all dst created in ipv4 code do not use the dst gc
anymore and will be destroyed at the point when refcnt drops to 0.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch checks all the calls to
dst_hold()/skb_dst_force()/dst_clone()/dst_use() to see if
dst_hold_safe() is needed to avoid double free issue if dst
gc is removed and dst_release() directly destroys dst when
dst->__refcnt drops to 0.
In tx path, TCP hold sk->sk_rx_dst ref count and also hold sock_lock().
UDP and other similar protocols always hold refcount for
skb->_skb_refdst. So both paths seem to be safe.
In rx path, as it is lockless and skb_dst_set_noref() is likely to be
used, dst_hold_safe() should always be used when trying to hold dst.
In the routing code, if dst is held during an rcu protected session, it
is necessary to call dst_hold_safe() as the current dst might be in its
rcu grace period.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As the intend of this patch series is to completely remove dst gc,
we need to call dst_dev_put() to release the reference to dst->dev
when removing routes from fib because we won't keep the gc list anymore
and will lose the dst pointer right after removing the routes.
Without the gc list, there is no way to find all the dst's that have
dst->dev pointing to the going-down dev.
Hence, we are doing dst_dev_put() immediately before we lose the last
reference of the dst from the routing code. The next dst_check() will
trigger a route re-lookup to find another route (if there is any).
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In IPv4 routing code, fib_nh and fib_nh_exception can hold pointers
to struct rtable but they never increment dst->__refcnt.
This leads to the need of the dst garbage collector because when user
is done with this dst and calls dst_release(), it can only decrement
dst->__refcnt and can not free the dst even it sees dst->__refcnt
drops from 1 to 0 (unless DST_NOCACHE flag is set) because the routing
code might still hold reference to it.
And when the routing code tries to delete a route, it has to put the
dst to the gc_list if dst->__refcnt is not yet 0 and have a gc thread
running periodically to check on dst->__refcnt and finally to free dst
when refcnt becomes 0.
This patch increments dst->__refcnt when
fib_nh/fib_nh_exception holds reference to this dst and properly release
the dst when fib_nh/fib_nh_exception has been updated with a new dst.
This patch is a preparation in order to fully get rid of dst gc later.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This function should be called when removing routes from fib tree after
the dst gc is no longer in use.
We first mark DST_OBSOLETE_DEAD on this dst to make sure next
dst_ops->check() fails and returns NULL.
Secondly, as we no longer keep the gc_list, we need to properly
release dst->dev right at the moment when the dst is removed from
the fib/fib6 tree.
It does the following:
1. change dst->input and output pointers to dst_discard/dst_dscard_out to
discard all packets
2. replace dst->dev with loopback interface
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The current mechanism of freeing dst is a bit complicated. dst has its
ref count and when user grabs the reference to the dst, the ref count is
properly taken in most cases except in IPv4/IPv6/decnet/xfrm routing
code due to some historic reasons.
If the reference to dst is always taken properly, we should be able to
simplify the logic in dst_release() to destroy dst when dst->__refcnt
drops from 1 to 0. And this should be the only condition to determine
if we can call dst_destroy().
And as dst is always ref counted, there is no need for a dst garbage
list to hold the dst entries that already get removed by the routing
code but are still held by other users. And the task to periodically
check the list to free dst if ref count become 0 is also not needed
anymore.
This patch introduces a temporary flag DST_NOGC(no garbage collector).
If it is set in the dst, dst_release() will call dst_destroy() when
dst->__refcnt drops to 0. dst_hold_safe() will also check for this flag
and do atomic_inc_not_zero() similar as DST_NOCACHE to avoid double free
issue.
This temporary flag is mainly used so that we can make the transition
component by component without breaking other parts.
This flag will be removed after all components are properly transitioned.
This patch also introduces a new function dst_release_immediate() which
destroys dst without waiting on the rcu when refcnt drops to 0. It will
be used in later patches.
Follow-up patches will correct all the places to properly take ref count
on dst and mark DST_NOGC. dst_release() or dst_release_immediate() will
be used to release the dst instead of dst_free() and its related
functions.
And final clean-up patch will remove the DST_NOGC flag.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Existing ipv4/6_blackhole_route() code generates a blackhole route
with dst->dev pointing to the passed in dst->dev.
It is not necessary to hold reference to the passed in dst->dev
because the packets going through this route are dropped anyway.
A loopback interface is good enough so that we don't need to worry about
releasing this dst->dev when this dev is going down.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In udp_v4/6_early_demux() code, we try to hold dst->__refcnt for
dst with DST_NOCACHE flag. This is because later in udp_sk_rx_dst_set()
function, we will try to cache this dst in sk for connected case.
However, a better way to achieve this is to not try to hold dst in
early_demux(), but in udp_sk_rx_dst_set(), call dst_hold_safe(). This
approach is also more consistant with how tcp is handling it. And it
will make later changes simpler.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In ipv6 tx path, rcu_read_lock() is taken so that dst won't get freed
during the execution of ip6_fragment(). Hence, no need to hold dst in
it.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Merge tag 'led_fixes_for_4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds
Pull LED fixes from Jacek Anaszewski:
"Two LED fixes:
- fix signal source assignment for leds-bcm6328
- revert patch that intended to fix LED behavior on suspend but it
had a side effect preventing suspend at all due to uevent being
sent on trigger removal"
* tag 'led_fixes_for_4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds:
Revert "leds: handle suspend/resume in heartbeat trigger"
leds: bcm6328: fix signal source assignment for leds 4 to 7
Here are some small gadget and xhci USB fixes for 4.12-rc6.
Nothing major, but one of the gadget patches does fix a reported oops,
and the xhci ones resolve reported problems. All have been in
linux-next with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'usb-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
Pull USB fixes from Greg KH:
"Here are some small gadget and xhci USB fixes for 4.12-rc6.
Nothing major, but one of the gadget patches does fix a reported oops,
and the xhci ones resolve reported problems. All have been in
linux-next with no reported issues"
* tag 'usb-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
USB: gadgetfs, dummy-hcd, net2280: fix locking for callbacks
usb: xhci: ASMedia ASM1042A chipset need shorts TX quirk
usb: xhci: Fix USB 3.1 supported protocol parsing
USB: gadget: fix GPF in gadgetfs
usb: gadget: composite: make sure to reactivate function on unbind
Here are some small Staging and IIO driver fixes for 4.12-rc6.
Nothing huge, just a few small driver fixes for reported issues. All
have been in linux-next with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'staging-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
Pull staging and IIO fixes from Greg KH:
"Here are some small staging and IIO driver fixes for 4.12-rc6.
Nothing huge, just a few small driver fixes for reported issues. All
have been in linux-next with no reported issues"
* tag 'staging-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
Staging: rtl8723bs: fix an error code in isFileReadable()
iio: buffer-dmaengine: Add missing header buffer_impl.h
iio: buffer-dma: Add missing header buffer_impl.h
iio: adc: meson-saradc: fix potential crash in meson_sar_adc_clear_fifo
iio: adc: mxs-lradc: Fix return value check in mxs_lradc_adc_probe()
iio: imu: inv_mpu6050: add accel lpf setting for chip >= MPU6500
staging: iio: ad7152: Fix deadlock in ad7152_write_raw_samp_freq()
fixups from Zheng, prompted by the ongoing y2038 work.
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Merge tag 'ceph-for-4.12-rc6' of git://github.com/ceph/ceph-client
Pull ceph fixes from Ilya Dryomov:
"A fix for an old ceph ->fh_to_* bug from Luis and two timestamp fixups
from Zheng, prompted by the ongoing y2038 work"
* tag 'ceph-for-4.12-rc6' of git://github.com/ceph/ceph-client:
ceph: unify inode i_ctime update
ceph: use current_kernel_time() to get request time stamp
ceph: check i_nlink while converting a file handle to dentry
* original hysteresis loop got broken by typo back in 2002; now
it never switches out of OPTTIME state. Fixed.
* critical levels for switching from OPTTIME to OPTSPACE and back
ought to be calculated once, at mount time.
* we should use mul_u64_u32_div() for those calculations, now that
->s_dsize is 64bit.
* to quote Kirk McKusick (in 1995 FreeBSD commit message):
The threshold for switching from time-space and space-time is too small
when minfree is 5%...so make it stay at space in this case.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
- Fix some bogus ASSERT failures on CONFIG_SMP=n and CONFIG_XFS_DEBUG=y.
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Merge tag 'xfs-4.12-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull xfs fix from Darrick Wong:
"One more bugfix for you for 4.12-rc6 to fix something that came up in
an earlier rc:
- Fix some bogus ASSERT failures on CONFIG_SMP=n and CONFIG_XFS_DEBUG=y"
* tag 'xfs-4.12-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: fix spurious spin_is_locked() assert failures on non-smp kernels
Pull ufs fixes from Al Viro:
"Fix assorted ufs bugs: a couple of deadlocks, fs corruption in
truncate(), oopsen on tail unpacking and truncate when racing with
vmscan, mild fs corruption (free blocks stats summary buggered, *BSD
fsck would complain and fix), several instances of broken logics
around reserved blocks (starting with "check almost never triggers
when it should" and then there are issues with sufficiently large
UFS2)"
[ Note: ufs hasn't gotten any loving in a long time, because nobody
really seems to use it. These ufs fixes are triggered by people
actually caring now, not some sudden influx of new bugs. - Linus ]
* 'ufs-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
ufs_truncate_blocks(): fix the case when size is in the last direct block
ufs: more deadlock prevention on tail unpacking
ufs: avoid grabbing ->truncate_mutex if possible
ufs_get_locked_page(): make sure we have buffer_heads
ufs: fix s_size/s_dsize users
ufs: fix reserved blocks check
ufs: make ufs_freespace() return signed
ufs: fix logics in "ufs: make fsck -f happy"
Pull vfs fixes from Al Viro:
"A couple of fixes; a leak in mntns_install() caught by Andrei (this
cycle regression) + d_invalidate() softlockup fix - that had been
reported by a bunch of people lately, but the problem is pretty old"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: don't forget to put old mntns in mntns_install
Hang/soft lockup in d_invalidate with simultaneous calls
Merge misc fixes from Andrew Morton:
"5 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
mm: correct the comment when reclaimed pages exceed the scanned pages
userfaultfd: shmem: handle coredumping in handle_userfault()
mm: numa: avoid waiting on freed migrated pages
swap: cond_resched in swap_cgroup_prepare()
mm/memory-failure.c: use compound_head() flags for huge pages
Commit e1587a4945 ("mm: vmpressure: fix sending wrong events on
underflow") declared that reclaimed pages exceed the scanned pages due
to the thp reclaim.
That is incorrect because THP will be spilt to normal page and loop
again, which will result in the scanned pages increment.
[akpm@linux-foundation.org: tweak comment text]
Link: http://lkml.kernel.org/r/1496824266-25235-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhongjiang <zhongjiang@huawei.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Anon and hugetlbfs handle FOLL_DUMP set by get_dump_page() internally to
__get_user_pages().
shmem as opposed has no special FOLL_DUMP handling there so
handle_mm_fault() is invoked without mmap_sem and ends up calling
handle_userfault() that isn't expecting to be invoked without mmap_sem
held.
This makes handle_userfault() fail immediately if invoked through
shmem_vm_ops->fault during coredumping and solves the problem.
The side effect is a BUG_ON with no lock held triggered by the
coredumping process which exits. Only 4.11 is affected, pre-4.11 anon
memory holes are skipped in __get_user_pages by checking FOLL_DUMP
explicitly against empty pagetables (mm/gup.c:no_page_table()).
It's zero cost as we already had a check for current->flags to prevent
futex to trigger userfaults during exit (PF_EXITING).
Link: http://lkml.kernel.org/r/20170615214838.27429-1-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: <stable@vger.kernel.org> [4.11+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In do_huge_pmd_numa_page(), we attempt to handle a migrating thp pmd by
waiting until the pmd is unlocked before we return and retry. However,
we can race with migrate_misplaced_transhuge_page():
// do_huge_pmd_numa_page // migrate_misplaced_transhuge_page()
// Holds 0 refs on page // Holds 2 refs on page
vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
/* ... */
if (pmd_trans_migrating(*vmf->pmd)) {
page = pmd_page(*vmf->pmd);
spin_unlock(vmf->ptl);
ptl = pmd_lock(mm, pmd);
if (page_count(page) != 2)) {
/* roll back */
}
/* ... */
mlock_migrate_page(new_page, page);
/* ... */
spin_unlock(ptl);
put_page(page);
put_page(page); // page freed here
wait_on_page_locked(page);
goto out;
}
This can result in the freed page having its waiters flag set
unexpectedly, which trips the PAGE_FLAGS_CHECK_AT_PREP checks in the
page alloc/free functions. This has been observed on arm64 KVM guests.
We can avoid this by having do_huge_pmd_numa_page() take a reference on
the page before dropping the pmd lock, mirroring what we do in
__migration_entry_wait().
When we hit the race, migrate_misplaced_transhuge_page() will see the
reference and abort the migration, as it may do today in other cases.
Fixes: b8916634b7 ("mm: Prevent parallel splits during THP migration")
Link: http://lkml.kernel.org/r/1497349722-6731-2-git-send-email-will.deacon@arm.com
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Steve Capper <steve.capper@arm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I saw need_resched() warnings when swapping on large swapfile (TBs)
because continuously allocating many pages in swap_cgroup_prepare() took
too long.
We already cond_resched when freeing page in swap_cgroup_swapoff(). Do
the same for the page allocation.
Link: http://lkml.kernel.org/r/20170604200109.17606-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memory_failure() chooses a recovery action function based on the page
flags. For huge pages it uses the tail page flags which don't have
anything interesting set, resulting in:
> Memory failure: 0x9be3b4: Unknown page state
> Memory failure: 0x9be3b4: recovery action for unknown page: Failed
Instead, save a copy of the head page's flags if this is a huge page,
this means if there are no relevant flags for this tail page, we use the
head pages flags instead. This results in the me_huge_page() recovery
action being called:
> Memory failure: 0x9b7969: recovery action for huge page: Delayed
For hugepages that have not yet been allocated, this allows the hugepage
to be dequeued.
Fixes: 524fca1e73 ("HWPOISON: fix misjudgement of page_action() for errors on mlocked pages")
Link: http://lkml.kernel.org/r/20170524130204.21845-1-james.morse@arm.com
Signed-off-by: James Morse <james.morse@arm.com>
Tested-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Three small fixes for recently merged code:
- remove a spurious WARN_ON when a PCI device has no of_node, it's allowed in
some circumstances for there to be no of_node.
- fix the offset for store EOI MMIOs in the XIVE interrupt controller.
- fix non-const WARN_ONs which were becoming BUGs due to them losing
BUGFLAG_WARNING in a recent cleanup patch.
Thanks to:
Alexey Kardashevskiy, Alistair Popple, Benjamin Herrenschmidt.
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Merge tag 'powerpc-4.12-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman:
"Three small fixes for recently merged code:
- remove a spurious WARN_ON when a PCI device has no of_node, it's
allowed in some circumstances for there to be no of_node.
- fix the offset for store EOI MMIOs in the XIVE interrupt
controller.
- fix non-const WARN_ONs which were becoming BUGs due to them losing
BUGFLAG_WARNING in a recent cleanup patch.
Thanks to: Alexey Kardashevskiy, Alistair Popple, Benjamin
Herrenschmidt"
* tag 'powerpc-4.12-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/debug: Add missing warn flag to WARN_ON's non-builtin path
powerpc/xive: Fix offset for store EOI MMIOs
powerpc/npu-dma: Remove spurious WARN_ON when a PCI device has no of_node
- Fix probing of precise_ip level for default cycles event, that
got broken recently on x86_64 when its arch code started
considering invalid requesting precise samples when not sampling
(i.e. when attr.sample_period == 0).
This also fixes another problem in s/390 where the precision
probing with sample_period == 0 returned precise_ip > 0, that
then, when setting up the real cycles event (not probing) would
return EOPNOTSUPP for precise_ip > 0 (as determined previously
by probing) and sample_period > 0.
These problems resulted in attr_precise not being set to the
highest precision available on x86.64 when no event was specified,
i.e. the canonical:
perf record ./workload
would end up using attr.precise_ip = 0. As a workaround this would
need to be done:
perf record -e cycles:P ./workload
And on s/390 it would plain not work, requiring using:
perf record -e cycles ./workload
as a workaround. (Arnaldo Carvalho de Melo)
- Fix perf build with ARCH=x86_64, when ARCH should be transformed
into ARCH=x86, just like with the main kernel Makefile and
tools/objtool's, i.e. use SRCARCH. (Jiada Wang)
- Avoid accessing uninitialized data structures when unwinding with
elfutils's libdw, making it more closely mimic libunwind's unwinder.
(Milian Wolff)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Merge tag 'perf-urgent-for-mingo-4.12-20170616' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/urgent
Pull perf/urgent fixes from Arnaldo Carvalho de Melo:
- Fix probing of precise_ip level for default cycles event, that
got broken recently on x86_64 when its arch code started
considering invalid requesting precise samples when not sampling
(i.e. when attr.sample_period == 0).
This also fixes another problem in s/390 where the precision
probing with sample_period == 0 returned precise_ip > 0, that
then, when setting up the real cycles event (not probing) would
return EOPNOTSUPP for precise_ip > 0 (as determined previously
by probing) and sample_period > 0.
These problems resulted in attr_precise not being set to the
highest precision available on x86.64 when no event was specified,
i.e. the canonical:
perf record ./workload
would end up using attr.precise_ip = 0. As a workaround this would
need to be done:
perf record -e cycles:P ./workload
And on s/390 it would plain not work, requiring using:
perf record -e cycles ./workload
as a workaround. (Arnaldo Carvalho de Melo)
- Fix perf build with ARCH=x86_64, when ARCH should be transformed
into ARCH=x86, just like with the main kernel Makefile and
tools/objtool's, i.e. use SRCARCH. (Jiada Wang)
- Avoid accessing uninitialized data structures when unwinding with
elfutils's libdw, making it more closely mimic libunwind's unwinder.
(Milian Wolff)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This series provide some updates and cleanups for mlx5 core and netdevice
driver.
From Eli Cohen, add a missing event string.
From Or Gerlitz, some checkpatch cleanups.
From Moni, Disalbe HW level LAG when SRIOV is enabled.
From Tariq, A code reuse cleanup in aRFS flow.
From Itay Aveksis, Typo fix.
From Gal Pressman, ethtool statistics updates and "update stats" deferred work optimizations.
From Majd Dibbiny, Fast unload support on kernel shutdown.
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Merge tag 'mlx5-updates-2017-06-16' of git://git.kernel.org/pub/scm/linux/kernel/git/saeed/linux
Saeed Mahameed says:
====================
Mellanox mlx5 updates and cleanups 2017-06-16
mlx5-updates-2017-06-16
This series provide some updates and cleanups for mlx5 core and netdevice
driver.
From Eli Cohen, add a missing event string.
From Or Gerlitz, some checkpatch cleanups.
From Moni, Disalbe HW level LAG when SRIOV is enabled.
From Tariq, A code reuse cleanup in aRFS flow.
From Itay Aveksis, Typo fix.
From Gal Pressman, ethtool statistics updates and "update stats" deferred work optimizations.
From Majd Dibbiny, Fast unload support on kernel shutdown.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Similarly to how cross-chip VLAN works, define a bitmap of multicast
group members for a switch, now including its DSA ports, so that
multicast traffic can be sent to all switches of the fabric.
A switch may drop the frames if no user port is a member.
This brings support for multicast in a multi-chip environment.
As of now, all switches of the fabric must support the multicast
operations in order to program a single fabric port.
Reported-by: Jason Cobham <jcobham@questertangent.com>
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Tested-by: Jason Cobham <jcobham@questertangent.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When booting into the kdump/kexec kernel, pHyp and vios
are not prepared for the initialization crq request and
a failover transport event is generated. This is not
handled correctly.
At this point in initialization the driver is still in
the 'probing' state and cannot handle a full reset of the
driver as is normally done for a failover transport event.
To correct this we catch driver resets while still in the
'probing' state and return EAGAIN. This results in the
driver tearing down the main crq and calling ibmvnic_init()
again.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the existing dn_route.c code, dn_route_output_slow() takes
dst->__refcnt before calling dn_insert_route() while dn_route_input_slow()
does not take dst->__refcnt before calling dn_insert_route().
This makes the whole routing code very buggy.
In dn_dst_check_expire(), dnrt_free() is called when rt expires. This
makes the routes inserted by dn_route_output_slow() not able to be
freed as the refcnt is not released.
In dn_dst_gc(), dnrt_drop() is called to release rt which could
potentially cause the dst->__refcnt to be dropped to -1.
In dn_run_flush(), dst_free() is called to release all the dst. Again,
it makes the dst inserted by dn_route_output_slow() not able to be
released and also, it does not wait on the rcu and could potentially
cause crash in the path where other users still refer to this dst.
This patch makes sure both input and output path do not take
dst->__refcnt before calling dn_insert_route() and also makes sure
dnrt_free()/dst_free() is called when removing dst from the hash table.
The only difference between those 2 calls is that dnrt_free() waits on
the rcu while dst_free() does not.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the existing dn_route.c code, dn_route_output_slow() takes
dst->__refcnt before calling dn_insert_route() while dn_route_input_slow()
does not take dst->__refcnt before calling dn_insert_route().
This makes the whole routing code very buggy.
In dn_dst_check_expire(), dnrt_free() is called when rt expires. This
makes the routes inserted by dn_route_output_slow() not able to be
freed as the refcnt is not released.
In dn_dst_gc(), dnrt_drop() is called to release rt which could
potentially cause the dst->__refcnt to be dropped to -1.
In dn_run_flush(), dst_free() is called to release all the dst. Again,
it makes the dst inserted by dn_route_output_slow() not able to be
released and also, it does not wait on the rcu and could potentially
cause crash in the path where other users still refer to this dst.
This patch makes sure both input and output path do not take
dst->__refcnt before calling dn_insert_route() and also makes sure
dnrt_free()/dst_free() is called when removing dst from the hash table.
The only difference between those 2 calls is that dnrt_free() waits on
the rcu while dst_free() does not.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Sowmini Varadhan says:
====================
rds: tcp: misc bug fixes
This series contains 2 bug fixes (patch2, patch3) and one bit of
code cleanup (patch1) identified during database testing
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Each time we get an incoming SYN to the RDS_TCP_PORT, the TCP
layer accepts the connection and then the rds_tcp_accept_one()
callback is invoked to process the incoming connection.
rds_tcp_accept_one() may reject the incoming syn for a number of
reasons, e.g., commit 1a0e100fb2 ("RDS: TCP: Force every connection
to be initiated by numerically smaller IP address"), or because
we are getting spammed by a malicious node that is triggering
a flood of connection attempts to RDS_TCP_PORT. If the incoming
syn is rejected, no data would have been sent on the TCP socket,
and we do not need to be in TIME_WAIT state, so we set linger on
the TCP socket before closing, thereby closing the socket efficiently
with a RST.
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Tested-by: Imanti Mendez <imanti.mendez@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
