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git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux
Pull dma-mapping fixes from Marek Szyprowski:
"Two more fixes for the corner cases in the DMA-mapping SWIOTLB code
(Peng Fan and Marek Szyprowski)"
* tag 'dma-mapping-7.3-2026-10-09' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
swiotlb: fix default_swiotlb_limit() for non-growable default pool
iommu/dma: skip swiotlb bounce for DMA_ATTR_MMIO in iommu_dma_map_phys
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs fixes from Christian Brauner:
"This contains fixes for the current development cycle.
All of them came out of a review of the mount code that started with a
bug report. The review modeled the corner cases of mount propagation,
unmounting and mount reference counting and turned up a lot of bugs.
Most of them years old. Most fixes come with a selftest.
- Rework connected mounts.
A mount that is unmounted together with its parent can stay
attached to the parent to keep its mountpoint covered. That happens
when the mountpoint is removed with rmdir(), unlink() or rename(),
when a detached tree is dissolved, and for locked mounts in any
umount that isn't synchronous, including the teardown of their
mount namespace. The parent then owns the child and drops it on its
own final mntput(). So any reference from the child's superblock
back to one of its ancestors becomes a cycle that is never freed.
A loop device backed by an image on a tmpfs and mounted on that
same tmpfs is enough. Remove the directory the tmpfs is mounted on
from the host, let the container's mount namespace exit, and the
loop device, the tmpfs and the filesystem on the loop device are
leaked for good. The same works with autofs, zram, ecryptfs,
binfmt_misc, fuse passthrough, zloop, a mass storage gadget and md,
and the selftests have reproducers for them. This has been possible
since v4.1. It is also why "put_mnt_ns(): leave mounts connected"
was reverted in -rc5. Keeping every mount of a dying mount
namespace connected made these cycles trivial to create.
Every unmounted mount is now detached from its parent. Where the
mountpoint has to stay covered the mount leaves a cover on the
parent instead, allocated together with the mount. A lookup on the
unmounted parent that hits a cover finds an empty immutable
directory or file on the private nullfs instance. Nothing leads
from a cover to another mount, so no unmounted mount owns another
one and no cycle can form.
This is visible to userspace. A formerly connected mount can no
longer be reached through its unmounted parent and ".." inside it
leads nowhere, as for every other lazily unmounted mount.
With that the private nullfs instance becomes reachable from
userspace, so it now refuses mounts on top, is mounted read-only,
and refuses fsnotify marks and file locks. Its inodes are shared by
every holder and a watch or a lock would otherwise reach across
users. may_decode_fh() now also decides its subtree check under a
single mount_lock hold, as a racing umount could otherwise let it
decode into what a locked child covered.
- umount:
* Don't silently unmount busy mounts.
Since v4.13 propagate_umount() takes down propagated copies of
the victim with children as long as each child is an overmount or
another copy of the victim, but propagate_mount_busy() only ever
checked copies without children or with just an overmount. A
container that moved a tree beneath its copy of a host mount lost
that tree from under its open file descriptor to a plain umount()
on the host. propagate_mount_busy() now applies the same rules,
walking each chain of copies once.
* Don't let a migrating task hide its reference from umount().
mnt_get_count() sums the per-cpu counters under mount_lock but
the mntget() and mntput() fast paths don't take it. A task that
takes a reference on a cpu the sum has already passed and drops
it after migrating to one the sum hasn't reached yet hides the
reference it held to begin with, and umount() succeeds with the
file still open. Gets and puts now live in separate per-cpu
counters and all puts are summed before all gets with a full
barrier in between, the way srcu_readers_active_idx_check() does
it. mntget() is unchanged and mntput() gains an smp_wmb().
* Check each submount for references right before unmounting it.
shrink_submounts() and mark_mounts_for_expiry() checked all their
victims up front. Unmounting the first could move a busy
overmount to where the next victim's propagated copy is looked up
and it was then unmounted without a check.
* Never expire a locked mount.
A shrinkable mount moved beneath a locked mount with
MOVE_MOUNT_BENEATH takes over the lock, and umount() of an
unlocked ancestor expired it and revealed what it covered. That
umount() now fails with EBUSY as it does for any other locked
child. A lazy umount still takes the whole tree.
- Overmounts and locked mounts:
* Unhash a dentry before detaching the mounts on it.
unlink(), rmdir() and rename() detach the mounts on the victim
but only d_delete() it once its inode is unlocked, a window that
includes an expedited RCU grace period. In between, a lookup from
a mount namespace in which the dentry is a mountpoint found it
hashed, positive and uncovered. Drop the dentry first, as
d_invalidate() already does.
* Don't reveal overmounted entries in refwalk.
A refwalk that had grabbed the dentry before the unlink never
rechecked it the way rcuwalk does with d_seq and mount_lock.
Without any artificial widening three walkers read the covered
file 27 times in a minute. step_into() now fails an unhashed
dentry marked DCACHE_CANT_MOUNT with -ESTALE and the walk is
retried.
* Keep covered mounts covered in OPEN_TREE_NAMESPACE.
Creating such a mount namespace only takes a user namespace and
the copy followed bind mount rules: no children without
AT_RECURSIVE and no unbindable mounts with it. An unprivileged
user could see what mounts covered in the source, such as the
parts of /proc and /sys that container runtimes mask. If the
caller doesn't own the source mount namespace a non-recursive
copy of a mount with something mounted below the requested
directory is now refused and a recursive copy includes unbindable
mounts, the way unshare() copies.
* Keep the lock on a mount that a propagated copy is moved beneath.
MNT_LOCKED moved to any mount that ended up beneath a locked
mount, propagated copies included. A host mount and umount on a
directory covered by a locked mount in a less privileged mount
namespace left that cover unlocked for the namespace's owner to
remove. Only mounts the caller places beneath take over the lock
now.
* Handle mount locking for automounts correctly. Which copies to
lock was decided by the mount namespace of the task that
triggered the automount. A task in a user namespace that
triggered one on a host mount through a file descriptor got the
host's own automount locked while its own copy stayed unlocked
and could have nosuid, nodev and noexec cleared. Use the owner of
the mount namespace the mount lands in.
- Use-after-free and crashes:
* Refuse an automount below a mount that is in no namespace.
The private clones overlayfs uses for its layers have the
MNT_NS_INTERNAL error pointer as their namespace, which
finish_automount() let through and count_mounts() dereferenced. A
fanotify filesystem mark on an overlayfs lower layer hands out
file descriptors on such a clone. With debugfs as the lower layer
opening "tracing" oopses with namespace_sem held for writing and
every mount operation on the system blocks from then on.
* Reset the old parent's ->overmount in mnt_change_mountpoint().
When propagate_umount() moved an overmount off a mount that a
file descriptor kept alive, MOVE_MOUNT_BENEATH through that
descriptor later followed the stale pointer into the freed
overmount.
* statmount() with STATMOUNT_BY_FD and pivot_root() read the parent
of a mount that may be unmounted and only held by a file
descriptor, while the parent's final mntput() can free it.
statmount() now reads it under mount_lock and pivot_root() first
checks that both mounts are in the caller's mount namespace.
* Queue a mount only once for mount notifications. A mount
reparented by one umount_tree() and taken down by the next under
the same namespace_sem hold, as in shrink_submounts(), was queued
twice. That cut the mounts queued in between out of notify_list
while it still pointed at them, and once they were freed every
later mount operation walked freed memory.
* Don't let a pseudo dentry become the root of a mount. A bind
mount of a bpf token file did that with a DCACHE_NORCU dentry,
which is freed without an RCU grace period while lockless path
walks may still look at it. Refuse to clone such a mount.
* Don't inherit MNT_UMOUNT in clone_mnt(). A bind mount of a lazily
unmounted nsfs or pidfs mount through its file descriptor started
out flagged as unmounted. Among other things __detach_mounts()
then dropped the namespace's reference on it, the mount outlived
its namespace and mount_setattr() through the descriptor read the
freed namespace. A recursive bind mount of such a mount also
copied the unmounted stack still attached to it. That now fails
with EINVAL, copying the mount itself still works.
* Remove the fsnotify marks of a mount namespace in free_mnt_ns()
instead of the RCU callback that frees the namespace, where
taking the group mutexes meant sleeping in softirq context.
- Propagation and copies:
* Keep a copied mount unbindable. Since v6.17 clone_mnt() didn't
copy the unbindable flag, so every mount namespace created with
CLONE_NEWNS had bindable copies of all unbindable mounts. This
had been fixed once before.
* Refuse MOVE_MOUNT_SET_GROUP on an unbindable mount. It made the
mount an unbindable slave, a state nothing else can produce, or
silently dropped the unbindable flag. CRIU applies MS_UNBINDABLE
after restoring sharing and isn't affected.
* Check a recursive bind mount for mount namespace loops.
Recursively bind mounting a tree from another mount namespace
could put a mount of a namespace's file inside that same
namespace, which then pins itself and all its mounts. Repeating
it leaks without limit, the reproducer took Shmem from 380 kB to
65916 kB. The copy is now checked with check_for_nsfs_mounts()
before it is grafted, as move_mount() does.
* Look at the topmost mount for a mount namespace file.
attach_recursive_mnt() never looked at the topmost mount of the
source's chain of overmounts. If that was the chain's only mount
namespace file an existing mount at a propagated destination got
buried below the root of the nsfs file where no path walk reaches
it.
* Don't put a mountpoint on a dentry that's being removed.
attach_recursive_mnt() makes a mountpoint of the source's root
without its inode lock, so a racing rmdir() of that directory
could leave a mount on it that nothing ever detaches.
d_set_mounted() now checks cant_mount() as well.
- nullfs:
* Take no inode lock for readdir of an immutable directory.
The root of every empty mount namespace is the same nullfs
directory and iterate_dir() held its i_rwsem across
->iterate_shared(). A reader whose buffer faults on a FUSE mount
of its own holds it for as long as its server wants, and with an
exclusive locker queued behind it every lookup that misses the
dcache, every create and every mount in that directory waits. One
user of an empty mount namespace stalls all others. Directories
with the new FOP_IMMUTABLE flag skip the lock.
* Refuse to reconfigure internal superblocks through fspick(),
MS_REMOUNT or the read-only remount that a synchronous umount()
of the root does. For nullfs only root in the initial user
namespace could do it, but the superblock is shared by every
mount namespace and the flags showed up in statfs() for all of
them.
* Don't update the access time on nullfs and refuse F_SET_RW_HINT
on an immutable inode.
- unshare: Free an nsproxy that was never installed with
nsproxy_free() when set_cred_ucounts() fails. put_nsproxy() dropped
active references that were never taken, which triggered a warning
and hid the caller's own namespaces from listns().
- Smaller changes: mount_setattr() checks the target before it walks
the tree to allocate peer group ids, unshare() puts the old
fs_struct before the old namespaces, dissolve_on_fput() drops the
file's reference to the tree itself, disconnect_mount() is
simplified and the documentation of the propagated unmount rule is
brought up to date"
* tag 'vfs-7.3-rc7.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (58 commits)
namespace: simplify disconnect_mount()
selftests/filesystems: test covered mounts
namespace: rework connected mounts
nullfs: add an empty immutable regular file
selftests/filesystems: check that reading the root of an empty mount namespace stalls nobody
selftests/filesystems: add a helper that holds a readdir in a page fault
readdir: take no inode lock on an immutable directory
nullfs: refuse file locks
fsnotify: let a filesystem refuse marks on its objects
namespace: nothing is mounted on or written through knullfs
namespace: keep the private nullfs instance in knullfs
fhandle: decide the subtree check under mount_lock
selftests/filesystems: check that an automount below an overlay layer is refused
selftests/filesystems: check the atime of the empty mount namespace root
selftests/filesystems: check that a lock lands on the right mount and stays
namespace: keep the lock on a mount that a propagated copy is moved beneath
namespace: never expire a locked mount
nullfs: don't update the access time
namespace: handle mount locking for automounts correctly
namespace: refuse an automount below a mount that is in no namespace
...
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Commit ad96ce3252db ("swiotlb: determine potential physical address
limit") changed default_swiotlb_limit() to return the maximum physical
address that could ever be used by dynamically allocated pools, so that
the value stays constant when CONFIG_SWIOTLB_DYNAMIC=y. However,
io_tlb_default_mem.phys_limit is returned even when the default pool
cannot grow, e.g. when swiotlb_init_remap() is called with a remap
callback.
This breaks Xen dom0 on x86: pci_xen_swiotlb_init() passes SWIOTLB_ANY
and xen_swiotlb_fixup(), so phys_limit is set to the top of dom0 memory,
although xen_swiotlb_fixup() makes the default pool below the 32-bit
boundary. xen_swiotlb_dma_supported() then rejects 32-bit DMA masks,
even though the bounce buffer is perfectly usable by such devices.
Return phys_limit only if the default pool can actually grow, otherwise
report the real end of the default pool, like in the
!CONFIG_SWIOTLB_DYNAMIC case.
Reported-by: Andreas Greve <andreas.greve@a-greve.de>
Reported-by: James Dingwall <james@dingwall.me.uk>
Fixes: ad96ce3252db ("swiotlb: determine potential physical address limit")
Closes: https://lore.kernel.org/xen-devel/f74668db-52fd-4575-8372-7bfdf10d62ac@a-greve.de/
Cc: stable@vger.kernel.org
Assisted-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Tested-by: James Dingwall <james@dingwall.me.uk>
Link: https://lore.kernel.org/all/20261005070518.1590097-1-m.szyprowski@samsung.com/
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux
Pull RCU fix from Paul McKenney:
"Fix spurious WARN_ON() for rcu_segcblist_n_cbs() in
cleanup_srcu_struct()
This issue was introduced by 78a38cbf6f20 ("srcu: Queue
sdp->work when the delay timer is successfully deleted")
during this merge window.
Enough people are hitting this that I am sending it now
rather than waiting for the next merge window. Especially
given that it is a simple one-liner"
* tag 'urgent.2026.10.01a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux:
srcu: Fix WARN_ON() for rcu_segcblist_n_cbs() in cleanup_srcu_struct()
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue fixes from Tejun Heo:
- Fix a NULL dereference in the chained work check when a kworker
queues work on a draining or destroying workqueue outside work item
execution.
* tag 'wq-for-7.3-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Fix NULL current_pwq deref in chained work check
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
- During CPU offline, the active mask drops the CPU before cpuset
updates the effective CPUs, so a task placement in that window could
find no active CPU in the top cpuset and dereference NULL. Restore
the NULL check.
- The cpuset v2-mode test read the subsystem's root pointer, which is
stale during a cgroup filesystem rebind, and the hotplug handler
evaluated it before taking the cpuset mutex. Record the mode in a
flag and test it under the mutex.
* tag 'cgroup-for-7.3-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup/cpuset: Call is_in_v2_mode() after acquiring cpuset_mutex in cpuset_handle_hotplug()
cgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus()
cgroup/cpuset: Don't access cpuset_cgrp_subsys.root in is_in_v2_mode()
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
- Taking a CPU offline could hang, or stall until the watchdog ejected
the BPF scheduler, when tasks on the dying CPU were still held by the
scheduler or sitting on a user dispatch queue. Re-enqueue them onto
the local queue when the runqueue goes offline so that the CPU pushes
them off like the other sched classes.
- The sequence number guarding against stale dispatches was per
runqueue, so a task re-enqueued on another CPU could get the same
number and a dispatch meant for its earlier instance was applied to
the new one. Use a per-task counter.
- A task dispatched to another CPU's local queue got its ops.dequeue()
only when picked to run and flagged as a core-sched pick. Call it at
insertion like for same-CPU dispatches.
* tag 'sched_ext-for-7.3-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: Generate qseq from a per-task counter
selftests/sched_ext: Add a test for ops.dequeue() on remote local DSQ moves
sched_ext: Call ops.dequeue() when a task arrives on a remote local DSQ
sched_ext: Fix CPU hotplug hang when a dying CPU's tasks sit in the BPF scheduler
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cpuset_handle_hotplug()
It is reported by sashiko that calling is_in_v2_mode() outside of
cpuset_mutex critical section in cpuset_handle_hotplug() can introduce
a TOCTOU race where cgroup hierarchy may have changed from v1 to v2 or
vice versa after is_in_v2_mode() is called leading to erroneously skip
the allocation of tmpmasks or incorrectly modify cpus_allowed masks,
resulting in cpuset state corruption. Fix that by calling is_in_v2_mode()
after acquiring the cpuset_mutex.
Fixes: b8d1b8ee93df ("cpuset: Allow v2 behavior in v1 cgroup")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk fix from Petr Mladek:
- Allow using Braille console with a serial console driver converted
to NBCON API
* tag 'printk-for-7.3-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
braille: nbcon: Allow to use a serial console with NBCON API as Braille console
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf events fixes from Ingo Molnar:
- Fix race between perf_event_exit_task() and perf_pending_task()
(Luo Gengkun)
- Fix perf header output management regressions (Ian Rogers)
- Require kernel access for text poke events (Zhengchuan Liang)
* tag 'perf-urgent-2026-10-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Require kernel access for text poke events
perf: Replace perf_event_header__init_id with full header init
perf: Fix race between perf_event_exit_task() and perf_pending_task()
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar:
- Don't run refcount kunit self-test when !CONFIG_KUNIT_ALL_TESTS
(Kuan-Wei Chiu)
- Fix futex private hash use-after-free on resize (Chris Mason)
* tag 'locking-urgent-2026-10-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
futex: Fix private hash use-after-free on resize
irq: Make refcount_interrupt kunit test selectable
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finish_dispatch() uses the qseq embedded in p->scx.ops_state to tell
whether the QUEUED instance of a task it's about to claim is the one
scx_bpf_dsq_insert() saw. qseq is generated from rq->scx.ops_qseq, but
the counters of different rqs are independent, so if a task is dequeued
and re-enqueued on a different rq between scx_bpf_dsq_insert() and
finish_dispatch(), the new QUEUED instance can end up with the same
qseq as the old one:
CPU X CPU Z
----- -----
enqueue p on rq A, qseq = N
ops.dispatch()
scx_bpf_dsq_insert(p)
records qseq N
sched_setaffinity(p)
dequeue p from rq A
enqueue p on rq B, qseq = N
finish_dispatch(p, N)
qseq matches, p is claimed
The claim itself is still atomic so the core stays consistent, but an
insert issued for a previous QUEUED instance gets applied to a new one
which the BPF scheduler has just received through ops.enqueue(). This
breaks the guarantee that dispatches targeting a stale instance are
ignored.
Generate qseq from a per-task counter, p->scx.ops_qseq, instead so that
consecutive QUEUED instances of a task never share a qseq regardless of
which rq they're on. The counter is only updated in
scx_do_enqueue_task() with the task's rq locked, so no additional
synchronization is needed, and it fits in an existing hole in struct
sched_ext_entity on 64bit. Remove the now unused rq->scx.ops_qseq.
Never generate qseq 0. NONE and DISPATCHING don't carry a qseq, so
scx_bpf_dsq_insert() on a task in either state records 0. With a
per-task counter, every task's first QUEUED instance would otherwise get
qseq 0 and could be claimed by such an insert. Wrap the counter where
the QSEQ field wraps so that it can't reach a value that shifts to 0 on
32bit either.
Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class")
Cc: stable@vger.kernel.org # v6.12+
Assisted-by: Claude:claude-opus-5.5
Signed-off-by: Kuba Piecuch <jpiecuch@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull probes fixes from Masami Hiramatsu:
- fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching()
Exit handlers early if !rcu_is_watching() to prevent potential
use-after-free during unregistration in idle/quiescent states. Switch
to guard(rcu_sched_notrace) to avoid fast-path lockdep overhead and
recursion while ensuring safe grace period synchronization.
- kprobes: Skip disarmed probes when checking optkprobe overlap
Continue past disarmed or unprepared probes in get_optimized_kprobe()
to find active optimized probes. This avoids overwriting active jump
displacements which can lead to panic.
* tag 'probes-fixes-v7.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
kprobes: Skip disarmed probes when checking optkprobe overlap
fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching()
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Pull bpf fixes from Alexei Starovoitov:
- Fix overflow of backward jump offset in constant blinding
(Alexei Starovoitov)
- Fix packet range of packet pointers sharing an id when var_off
tightens umax of one pointer and not the other (Alexei Starovoitov)
- Fix objects stuck in free_by_rcu_ttrace list of bpf memalloc
(Alexei Starovoitov)
- Fix use-after-free of progs detached from busy trampolines: wait for
an RCU tasks grace period before freeing trampoline progs, and patch
detached progs out of trampoline images that are still in use
(Florent Revest)
- Hold map BTF for the memory allocator destructor record to fix UAF in
deferred bpf_mem_alloc destruction (Kumar Kartikeya Dwivedi)
- Fix missing migration protection in resizable hashtab
lookup_and_delete batch operation (Ömer Mete Kaya)
* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
bpf: Fix missing migration protection in __rhtab_map_lookup_and_delete_batch()
selftests/bpf: Add a test for objects stuck in free_by_rcu_ttrace
bpf: Fix objects stuck in free_by_rcu_ttrace
bpf: Factor out __do_call_rcu_ttrace()
selftests/bpf: Test packet range of pointers sharing an id
bpf: Fix packet range of pointers sharing an id
selftests/bpf: Detach a trampoline prog while a task sleeps before it
bpf: Skip detached progs in trampoline images that are still in use
bpf: Wait for an RCU tasks grace period before freeing trampoline progs
bpf: Hold map BTF for the memory allocator destructor record
bpf: Fix overflow of jump offset in constant blinding
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With commit 2125c0034c5d ("cgroup/cpuset: Make cpuset hotplug processing
synchronous"), the cpuset hotplug operation becomes synchronous. That
commit also removes the code that handles race between cpuset_hotplug_work
and cpu hotplug notifier with the assumption that race is now gone.
Later commit 7a0aabd9ce69 ("cgroup/cpuset: Always use cpu_active_mask")
updates the cpuset code to always use cpu_active_mask instead of
cpu_online_mask in some places including guarantee_online_cpus() which
is renamed to guarantee_active_cpus() in that commit.
In the case of CPU offline operation, cpu_active_mask is updated
first in sched_cpu_deactivate() to remove the offline CPU before
cpuset_handle_hotplug() is called to update the effective_cpus of the
affected cpusets. The cpu_online_mask is updated after that near the end
of the offline operation to remove the offline CPU. As a result, the race
comes back and the top cpuset may not have any active CPU leading to NULL
pointer dereference during the race window when guarantee_active_cpus()
is called after cpu_active_mask is updated to remove the CPU to be torn
down but before cpuset_handle_hotplug() is able to properly update the
effective_cpus of the top cpuset.
Fix this by adding back the NULL cs check to avoid this problem.
Fixes: 7a0aabd9ce69 ("cgroup/cpuset: Always use cpu_active_mask")
Cc: stable@vger.kernel.org # v6.16+
Reported-by: Farhad Alemi <farhad.alemi@berkeley.edu>
Link: https://lore.kernel.org/lkml/CA+0ovChh3VjsKN1g+ZGjwwY2fGTpP7uD+aCCByLj5Qbymw=bfQ@mail.gmail.com
Signed-off-by: Waiman Long <longman@redhat.com>
Tested-by: Farhad Alemi <farhad.alemi@berkeley.edu>
Signed-off-by: Tejun Heo <tj@kernel.org>
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bpf_mem_cache_free_rcu() uses this_cpu_ptr() which requires migration
to be disabled. All callers of rhtab_delete_elem() disable migration
except __rhtab_map_lookup_and_delete_batch(), which calls it under
rcu_read_lock() only.
On CONFIG_PREEMPT_RCU, rcu_read_lock() does not disable preemption or
migration, so the task can migrate between CPUs during the delete loop,
causing this_cpu_ptr() to trigger:
BUG: using smp_processor_id() in preemptible [00000000] code
Fix by wrapping the delete loop in migrate_disable()/migrate_enable()
in __rhtab_map_lookup_and_delete_batch(), matching the migration
protection that the other callers already provide.
Fixes: 818e00848227 ("bpf: Implement iteration ops for resizable hashtab")
Reported-by: syzbot+fd7e415d891073b83e1f@syzkaller.appspotmail.com
Signed-off-by: Ömer Mete Kaya <omermetekaya0@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://patch.msgid.link/20260929081609.557899-1-omermetekaya0@gmail.com
Closes: https://syzkaller.appspot.com/bug?extid=fd7e415d891073b83e1f
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poll_state_synchronize_rcu(mm->futex.phash.batches) is used by
futex_ref_drop() to check that a grace period has passed since the
current hash was published. This relies on batches referencing a grace
period which started after the hash pointer was assigned.
__futex_pivot_hash() sets mmph->batches before it replaces mmph->hash:
scoped_guard(rcu) {
mmph->batches = get_state_synchronize_rcu();
rcu_assign_pointer(mmph->hash, new);
}
The scoped_guard(rcu) doesn't stop new grace periods from starting, and
if one starts between those two assignments, futex_ref_drop() can move
forward while a reader still holds a pointer to the old hash.
Fix things by setting mmph->batches after assigning mmph->hash. The
scoped_guard(rcu) isn't needed, so let's drop that as well.
Fixes: 56180dd20c19 ("futex: Use RCU-based per-CPU reference counting instead of rcuref_t")
Assisted-by: kres
Signed-off-by: Chris Mason <mason@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://patch.msgid.link/20261001135022.2220288-1-mason@kernel.org
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Currently, refcount_interrupt_test is built unconditionally when
CONFIG_KUNIT is enabled, causing it to run unexpectedly during boot.
Fix this by introducing CONFIG_REFCOUNT_INTERRUPT_KUNIT_TEST so the
test can be configured independently, following standard kunit
practices.
Fixes: 07a88e2bcd5b ("irq: Add KUnit test for refcounted interrupt enable/disable")
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Reviewed-by: Boqun Feng <boqun@kernel.org>
Link: https://patch.msgid.link/20261001082519.16195-2-boqun@kernel.org
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The Braille console is not registered in console_list. Instead, it is
integrated with the virtual terminal (VT) and shows what is displayed
on the terminal. It writes the data using con->write*() callback
of the associated serial console driver.
braille_write() is called from the VT code under console_lock().
The associated serial console driver can be converted to the NBCON API
though. The situation is similar to flushing nbcon consoles in the legacy
loop when some boot consoles are still registered, see
nbcon_legacy_emit_next_record().
But there is a big difference though. braille_write() is not directly
called from the code paths flushing registered consoles. The VT code
expects that braille_write() succeeds. It does not replay the message
when it can't acquire the ownership. As a result, braille_write():
+ must try harder to get the ownership.
+ has to be synchronized only against non-printk serial console
which depend nbcon_device_try_acquire() using NBCON_PRIO_NORMAL.
Let's look at it from another side and try to simulate the original
locking using the NBCON API:
1. Take con->device_lock(), aka the port->lock in the legacy serial
console driver.
2. Acquire nbcon context to provide some synchronization for a panic()
context. Use NBCON_PRIO_NORMAL because it contends only with
nbcon_device_try_acquire() users. Do it in a busy loop. It should
always succeed when con->device_lock() succeeded because all other
users do the same. The only exception is when the context get acquired
by a CPU handling panic.
3. In panic, disable interrupts and try to acquire the nbcon context.
Use NBCON_PRIO_PANIC. And try even an unsafe takeover because
otherwise the Braille console won't see the text shown during panic().
It is similar to the oops_in_progress/trylock handling in the legacy
serial console driver.
Finally, avoid the newline prepending logic in the existing serial console
drivers when they are used as a Braille console. As explained above,
the Braille console shows the last modified line on the terminal (VT).
braille_write() is called when single characters are added. Most
messages are not ended by newline. Anyway, the VT code does not have
logic to reply partially printed messages.
Fixes: 13189fa73afa ("printk: nbcon: Rely on kthreads for normal operation")
Reviewed-by: John Ogness <john.ogness@linutronix.de>
[pmladek@suse.com: Remove white space changes in braille_register_console(). Typo fix.]
Link: https://patch.msgid.link/20261001140727.124398-2-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
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On x86, an optkprobe at A replaces five bytes with a jump. If a disabled
probe B is at A+2, get_optimized_kprobe() stops at B when arming a new
probe C at A+4. It leaves A optimized:
A A+1 A+2 A+3 A+4
A's jump | e9 | d0 | d1 | d2 | d3 |
after C | e9 | d0 | d1 | d2 | cc |
The INT3 for C overwrites the last byte of A's jump displacement, so
execution can jump to the wrong address. B can have prepared optinsns
while disarmed, but has no jump to unoptimize.
Continue past disarmed and unprepared probes to find the active optimized
probe before arming a probe in its jump.
Link: https://lore.kernel.org/all/20260930053618.104498-1-leon.hwang@linux.dev/
Fixes: afd66255b9a4 ("kprobes: Introduce kprobes jump optimization")
Cc: stable@vger.kernel.org
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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The WARN_ON() added by commit 78a38cbf6f20 ("srcu: Queue sdp->work
when the delay timer is successfully deleted") uses rcu_segcblist_n_cbs()
to detect callbacks that srcu_barrier() failed to wait for. However, the
->len counter is decremented only at the end of srcu_invoke_callbacks(),
after the invoking loop has finished. Since srcu_barrier() can return
right after the barrier callback is invoked, cleanup_srcu_struct() can see
a non-zero n_cbs even though the cblist is already physically empty,
falsely triggering the WARN_ON() together with a still-pending delay_work
timer.
This can be triggered as follows, as seen in the syzbot report against
kvm_destroy_vm() -> cleanup_srcu_struct(&kvm->srcu):
1. call_srcu(&kvm->srcu, &bus->rcu, __free_bus) starts SRCU grace
period GP1.
2. GP1 ends: a delay timer is armed and sdp->work is queued, but
sdp->work has not run yet.
3. Another call_srcu(&kvm->srcu, &bus->rcu, __free_bus) call invokes
srcu_segcblist_advance(), which moves the GP1 callback to
RCU_DONE_TAIL, and starts SRCU grace period GP2.
4. srcu_barrier() is called. It queues its barrier callback after the
GP2 callback and waits for srcu_invoke_callbacks() to invoke it.
5. GP2 ends: another delay timer is armed, and the sdp->work queued in
step 2 begins to run. Its srcu_invoke_callbacks() call invokes
srcu_segcblist_advance() again, moving the GP2 and barrier callbacks
to RCU_DONE_TAIL as well, and then invokes all of them. However,
rcu_segcblist_add_len(), which updates srcu_cblist's ->len, has not
run yet at this point.
6. srcu_barrier() returns once its callback has been invoked, and
cleanup_srcu_struct() starts running. It finds the delay timer
armed in step 5 still pending and srcu_cblist's ->len still
non-zero (because step 5 has not reached rcu_segcblist_add_len()
yet), and WARN_ON() fires even though every callback has actually
been invoked.
Use rcu_segcblist_empty(), which checks the actual head of the cblist,
instead of rcu_segcblist_n_cbs(), which checks the racy ->len counter.
Callbacks that have genuinely not been invoked yet still leave the list
non-empty, so the WARN_ON() still catches callers that skip srcu_barrier()
or queue callbacks after it.
Link: https://lore.kernel.org/rcu/e6350377085ddd85d6ef00d8e9a67bd50c762d3c@linux.dev/T/#t
Reported-by: syzbot+d4faf7db59e11f6fd1ab@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d4faf7db59e11f6fd1ab
Fixes: 78a38cbf6f20 ("srcu: Queue sdp->work when the delay timer is successfully deleted")
Suggested-by: Zqiang <qiang.zhang@linux.dev>
Signed-off-by: Sunho Park <shpark061104@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Sean Christopherson <seanjc@google.com>
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do_call_rcu_ttrace() returns early when call_rcu_ttrace_in_progress is set
and leaves the objects in free_by_rcu_ttrace. __free_rcu() frees
waiting_for_gp_ttrace only and clears the flag. Hence the objects that
free_bulk() or __free_by_rcu() added while RCU tasks trace GP was in flight
stay in free_by_rcu_ttrace until free_bulk() or alloc_bulk() is called for
the same bpf_mem_cache again, which may never happen. The number of such
objects is not bounded.
Turn call_rcu_ttrace_in_progress into three states:
0 - idle
1 - __free_rcu() is queued
2 - __free_rcu() is queued and free_by_rcu_ttrace got more objects since
do_call_rcu_ttrace() sets 2. __free_rcu() does cmpxchg(1 -> 0) and starts
the next GP when it fails. It cannot clear the flag first and check
free_by_rcu_ttrace later, since bpf_mem_alloc_destroy() frees bpf_mem_cache
without waiting for RCU callbacks when the flag is zero.
Now __free_rcu() queues itself, so the one that didn't see 'draining' may
do call_rcu_tasks_trace() after rcu_barrier_tasks_trace() in
free_mem_alloc(). Queue it under rcu_read_lock() and do synchronize_rcu()
before the barriers. Calling rcu_barrier_tasks_trace() twice works too, but
creating and destroying hash maps in a loop on many cpus slows down to one
free_mem_alloc() per GP and kworkers pile up.
Fixes: 8d5a8011b35d ("bpf: Batch call_rcu callbacks instead of SLAB_TYPESAFE_BY_RCU.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20260930095920.601738-3-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
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Move the part of do_call_rcu_ttrace() that runs after
call_rcu_ttrace_in_progress is set into __do_call_rcu_ttrace().
The next patch will call it from __free_rcu().
No functional change.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20260930095920.601738-2-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
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Since commit 022ac0750883 ("bpf: use reg->var_off instead of reg->off
for pointers"), find_good_pkt_pointers() sets the range of all packet
pointers sharing an id from the umax of the compared pointer, and
check_packet_access() requires umax + off + size <= range. That assumes
the umax of two such pointers differ by exactly their constant distance.
reg_bounds_sync() breaks it when var_off tightens one umax and not the
other:
r4 &= 0x38
if r4 > 50 goto exit ; umax 50, var_off (0x0; 0x38)
r5 = pkt + r4 ; umax 50
r6 = r5
r6 += 8 ; umax 56, not 58
Comparing r6 with pkt_end sets the range to 56, and the valid 8-byte
load at r5 is rejected (50 + 8 > 56). Comparing r5 sets it to 50, and
the out-of-bounds 1-byte load at r6 - 7, i.e. r5 + 1, is accepted
(56 - 7 + 1 <= 50).
Don't call reg_bounds_sync() on a packet pointer that keeps its id (a
constant was added or subtracted) or its range (an unknown non-negative
value was subtracted), so that var_off cannot tighten its umax. Only
update the 32-bit bounds from var_off: reg_bounds_sanity_check() wants
them constant when the lower half of var_off is, e.g. for pkt + 8.
This relies on nothing else changing the 64-bit bounds of a packet
pointer, which holds today.
var_off of such a pointer is no longer narrowed by its bounds. Adjust
three verifier_align expectations; the low bits, which the alignment
checks use, don't change. veristat on the selftests shows no verdict
changes and +0.8% insns in test_cls_redirect_subprogs.
Fixes: 022ac0750883 ("bpf: use reg->var_off instead of reg->off for pointers")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20261001145255.855630-1-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl
Pull sysctl fixes from Joel Granados:
"Fix sysctl jiffies conversions errors introduced in 2dc164a48e6f
("sysctl: Create converter functions with two new macros")
- Ensure that mult_hz does *not* wrap
- Ensure we pass just the magnitude for the negative branch in
proc_int_k2u_conv_kop"
* tag 'sysctl-7.03-fixes-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
time/jiffies: Saturate in mult_hz() instead of wrapping
sysctl: Negate before converting in the int read path
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Active references on the namespaces of an nsproxy are taken when the
nsproxy is installed into a task in switch_task_namespaces() and
copy_namespaces() and dropped again by put_nsproxy() through
deactivate_nsproxy().
But ksys_unshare() calls put_nsproxy() on an nsproxy that was never
installed when set_cred_ucounts() fails. The new namespaces of that
nsproxy go from zero to minus one and the namespaces shared with the
caller lose a reference that belongs to the nsproxy the caller keeps
using:
WARNING: kernel/nscommon.c:171 at __ns_ref_active_put+0x1cd/0x230
nsproxy_ns_active_put
deactivate_nsproxy
ksys_unshare
Afterwards the namespaces the caller lives in aren't listed by listns()
anymore. set_cred_ucounts() only fails when alloc_ucounts() can't
allocate and it only allocates when the real uid of the caller differs
from its effective uid.
Commit cefd55bd2159 ("nsproxy: fix free_nsproxy() and simplify
create_new_namespaces()") separated the two cases on purpose.
nsproxy_free() frees an nsproxy that was prepared but never installed
and that's what a failed setns() uses in put_nsset(). Export it and use
it for a failed unshare() as well.
Fixes: a98621a0f187 ("unshare: fix nsproxy leak in ksys_unshare() on set_cred_ucounts() failure")
Cc: stable@vger.kernel.org # v7.1+
Link: https://patch.msgid.link/20260930-work-mount-fixes-3-v1-16-be34c83956ae@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Perf events with exclude_kernel=1 can be opened without kernel perf
access. However, exclude_kernel does not suppress text-poke sideband
records. Every PERF_RECORD_TEXT_POKE is marked PERF_RECORD_MISC_KERNEL
and contains a raw kernel instruction address.
An unprivileged task can therefore open and mmap a task-local software
event with text_poke=1. Both opening a count-only tracepoint event and
configuring UDP GRO for ESP-in-UDP cause updates to inline static calls;
the observer receives the relocated addresses of the modified instructions.
For a known kernel image, any such address reveals the runtime kernel
text base despite KASLR.
Call perf_allow_kernel() whenever attr.text_poke is set, regardless of
exclude_kernel. Events that neither monitor kernel execution nor request
text-poke records retain their existing permissions.
Fixes: e17d43b93e54 ("perf: Add perf text poke event")
Assisted-by: LLM
Signed-off-by: Zhengchuan Liang <zcliangcn@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/99131354c41e23188f778b92f90363775b482395.1790573390.git.zcliangcn@gmail.com
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perf_iterate_sb() invokes its callback for each matching perf_event on
the CPU and task context, passing a shared caller-allocated event
structure.
perf_event_header__init_id() mutated header->size in place by adding
event->id_header_size, requiring sideband output callbacks to save and
restore header fields across iterations. Three sideband callbacks failed
to save and restore header.size around perf_event_header__init_id():
- perf_event_ksymbol_output()
- perf_event_bpf_output()
- perf_event_text_poke_output()
When multiple events with attr.ksymbol, attr.bpf_event, or
attr.text_poke and sample_id_all are active on the same CPU, each
subsequent event receives a record whose header.size is inflated by all
preceding events' id_header_size values while only a single id_sample is
written, leaving uninitialized ring-buffer bytes at the end of the
record and causing userspace perf to fail with -EFAULT ("Bad address")
when parsing the sample_id trailer.
Similarly, perf_event_mmap_output() set PERF_RECORD_MISC_MMAP_BUILD_ID
in mmap_event->event_id.header.misc when event->attr.build_id was
enabled, but only saved and restored header.size and header.type. If an
event with attr.build_id was followed by an event with attr.mmap2 and
!attr.build_id, the second event received PERF_RECORD_MISC_MMAP_BUILD_ID
in header.misc while its payload contained maj/min/ino/ino_generation
instead of a build ID.
Rather than splitting header initialization between callers and output
callbacks and saving/restoring mutated header fields, replace
perf_event_header__init_id() with perf_event_header__init(), which
initializes header->type, header->misc, and header->size alongside the
sample_id fields on each invocation.
Fixes: 76193a94522f ("perf, bpf: Introduce PERF_RECORD_KSYMBOL")
Fixes: 6ee52e2a3fe4 ("perf, bpf: Introduce PERF_RECORD_BPF_EVENT")
Fixes: e17d43b93e54 ("perf: Add perf text poke event")
Fixes: 88a16a130933 ("perf: Add build id data in mmap2 event")
Assisted-by: Antigravity:gemini-3.1-pro
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260929222332.973435-1-irogers@google.com
Cc: stable@vger.kernel.org
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A race condition exists between perf_event_exit_task() and
perf_pending_task() during begin_new_exec().
During begin_new_exec(), perf_event_exit_task() may be called, and the
PF_EXITING flag is not set on task. So perf_sigtrap() continues to execute
and triggers WARN_ON_ONCE(event->ctx->task != current).
Since both task exit and exec paths can call perf_event_exit_task() which
sets ctx->task to TASK_TOMBSTONE, fix this by explicitly checking if
event->ctx->task equals TASK_TOMBSTONE and dropping the redundant
PF_EXITING check.
Fixes: 97ba62b27867 ("perf: Add support for SIGTRAP on perf events")
Signed-off-by: Luo Gengkun <luogengkun2@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260920075026.990582-1-luogengkun2@huawei.com
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