<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/include, branch v6.6.127</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v6.6.127</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v6.6.127'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2026-02-19T15:28:28+00:00</updated>
<entry>
<title>net: tunnel: make skb_vlan_inet_prepare() return drop reasons</title>
<updated>2026-02-19T15:28:28+00:00</updated>
<author>
<name>Menglong Dong</name>
<email>menglong8.dong@gmail.com</email>
</author>
<published>2024-10-09T02:28:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=f478b8239d6564b20bbf2972e441c31f945a2b76'/>
<id>urn:sha1:f478b8239d6564b20bbf2972e441c31f945a2b76</id>
<content type='text'>
[ Upstream commit 9990ddf47d4168088e2246c3d418bf526e40830d ]

Make skb_vlan_inet_prepare return the skb drop reasons, which is just
what pskb_may_pull_reason() returns. Meanwhile, adjust all the call of
it.

Signed-off-by: Menglong Dong &lt;dongml2@chinatelecom.cn&gt;
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>mm/hugetlb: fix excessive IPI broadcasts when unsharing PMD tables using mmu_gather</title>
<updated>2026-02-19T15:28:26+00:00</updated>
<author>
<name>David Hildenbrand (Red Hat)</name>
<email>david@kernel.org</email>
</author>
<published>2025-12-23T21:40:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=ff37dd18ce7739a26aab0cc2d31006a45e6bde63'/>
<id>urn:sha1:ff37dd18ce7739a26aab0cc2d31006a45e6bde63</id>
<content type='text'>
commit 8ce720d5bd91e9dc16db3604aa4b1bf76770a9a1 upstream.

As reported, ever since commit 1013af4f585f ("mm/hugetlb: fix
huge_pmd_unshare() vs GUP-fast race") we can end up in some situations
where we perform so many IPI broadcasts when unsharing hugetlb PMD page
tables that it severely regresses some workloads.

In particular, when we fork()+exit(), or when we munmap() a large
area backed by many shared PMD tables, we perform one IPI broadcast per
unshared PMD table.

There are two optimizations to be had:

(1) When we process (unshare) multiple such PMD tables, such as during
    exit(), it is sufficient to send a single IPI broadcast (as long as
    we respect locking rules) instead of one per PMD table.

    Locking prevents that any of these PMD tables could get reused before
    we drop the lock.

(2) When we are not the last sharer (&gt; 2 users including us), there is
    no need to send the IPI broadcast. The shared PMD tables cannot
    become exclusive (fully unshared) before an IPI will be broadcasted
    by the last sharer.

    Concurrent GUP-fast could walk into a PMD table just before we
    unshared it. It could then succeed in grabbing a page from the
    shared page table even after munmap() etc succeeded (and supressed
    an IPI). But there is not difference compared to GUP-fast just
    sleeping for a while after grabbing the page and re-enabling IRQs.

    Most importantly, GUP-fast will never walk into page tables that are
    no-longer shared, because the last sharer will issue an IPI
    broadcast.

    (if ever required, checking whether the PUD changed in GUP-fast
     after grabbing the page like we do in the PTE case could handle
     this)

So let's rework PMD sharing TLB flushing + IPI sync to use the mmu_gather
infrastructure so we can implement these optimizations and demystify the
code at least a bit. Extend the mmu_gather infrastructure to be able to
deal with our special hugetlb PMD table sharing implementation.

To make initialization of the mmu_gather easier when working on a single
VMA (in particular, when dealing with hugetlb), provide
tlb_gather_mmu_vma().

We'll consolidate the handling for (full) unsharing of PMD tables in
tlb_unshare_pmd_ptdesc() and tlb_flush_unshared_tables(), and track
in "struct mmu_gather" whether we had (full) unsharing of PMD tables.

Because locking is very special (concurrent unsharing+reuse must be
prevented), we disallow deferring flushing to tlb_finish_mmu() and instead
require an explicit earlier call to tlb_flush_unshared_tables().

From hugetlb code, we call huge_pmd_unshare_flush() where we make sure
that the expected lock protecting us from concurrent unsharing+reuse is
still held.

Check with a VM_WARN_ON_ONCE() in tlb_finish_mmu() that
tlb_flush_unshared_tables() was properly called earlier.

Document it all properly.

Notes about tlb_remove_table_sync_one() interaction with unsharing:

There are two fairly tricky things:

(1) tlb_remove_table_sync_one() is a NOP on architectures without
    CONFIG_MMU_GATHER_RCU_TABLE_FREE.

    Here, the assumption is that the previous TLB flush would send an
    IPI to all relevant CPUs. Careful: some architectures like x86 only
    send IPIs to all relevant CPUs when tlb-&gt;freed_tables is set.

    The relevant architectures should be selecting
    MMU_GATHER_RCU_TABLE_FREE, but x86 might not do that in stable
    kernels and it might have been problematic before this patch.

    Also, the arch flushing behavior (independent of IPIs) is different
    when tlb-&gt;freed_tables is set. Do we have to enlighten them to also
    take care of tlb-&gt;unshared_tables? So far we didn't care, so
    hopefully we are fine. Of course, we could be setting
    tlb-&gt;freed_tables as well, but that might then unnecessarily flush
    too much, because the semantics of tlb-&gt;freed_tables are a bit
    fuzzy.

    This patch changes nothing in this regard.

(2) tlb_remove_table_sync_one() is not a NOP on architectures with
    CONFIG_MMU_GATHER_RCU_TABLE_FREE that actually don't need a sync.

    Take x86 as an example: in the common case (!pv, !X86_FEATURE_INVLPGB)
    we still issue IPIs during TLB flushes and don't actually need the
    second tlb_remove_table_sync_one().

    This optimized can be implemented on top of this, by checking e.g., in
    tlb_remove_table_sync_one() whether we really need IPIs. But as
    described in (1), it really must honor tlb-&gt;freed_tables then to
    send IPIs to all relevant CPUs.

Notes on TLB flushing changes:

(1) Flushing for non-shared PMD tables

    We're converting from flush_hugetlb_tlb_range() to
    tlb_remove_huge_tlb_entry(). Given that we properly initialize the
    MMU gather in tlb_gather_mmu_vma() to be hugetlb aware, similar to
    __unmap_hugepage_range(), that should be fine.

(2) Flushing for shared PMD tables

    We're converting from various things (flush_hugetlb_tlb_range(),
    tlb_flush_pmd_range(), flush_tlb_range()) to tlb_flush_pmd_range().

    tlb_flush_pmd_range() achieves the same that
    tlb_remove_huge_tlb_entry() would achieve in these scenarios.
    Note that tlb_remove_huge_tlb_entry() also calls
    __tlb_remove_tlb_entry(), however that is only implemented on
    powerpc, which does not support PMD table sharing.

    Similar to (1), tlb_gather_mmu_vma() should make sure that TLB
    flushing keeps on working as expected.

Further, note that the ptdesc_pmd_pts_dec() in huge_pmd_share() is not a
concern, as we are holding the i_mmap_lock the whole time, preventing
concurrent unsharing. That ptdesc_pmd_pts_dec() usage will be removed
separately as a cleanup later.

There are plenty more cleanups to be had, but they have to wait until
this is fixed.

[david@kernel.org: fix kerneldoc]
  Link: https://lkml.kernel.org/r/f223dd74-331c-412d-93fc-69e360a5006c@kernel.org
Link: https://lkml.kernel.org/r/20251223214037.580860-5-david@kernel.org
Fixes: 1013af4f585f ("mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race")
Signed-off-by: David Hildenbrand (Red Hat) &lt;david@kernel.org&gt;
Reported-by: "Uschakow, Stanislav" &lt;suschako@amazon.de&gt;
Closes: https://lore.kernel.org/all/4d3878531c76479d9f8ca9789dc6485d@amazon.de/
Tested-by: Laurence Oberman &lt;loberman@redhat.com&gt;
Acked-by: Harry Yoo &lt;harry.yoo@oracle.com&gt;
Reviewed-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Cc: Lance Yang &lt;lance.yang@linux.dev&gt;
Cc: Liu Shixin &lt;liushixin2@huawei.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Rik van Riel &lt;riel@surriel.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: David Hildenbrand (Arm) &lt;david@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>mm/hugetlb: fix hugetlb_pmd_shared()</title>
<updated>2026-02-19T15:28:26+00:00</updated>
<author>
<name>David Hildenbrand (Red Hat)</name>
<email>david@kernel.org</email>
</author>
<published>2025-12-23T21:40:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=51dcf459845fd28f5a0d83d408a379b274ec5cc5'/>
<id>urn:sha1:51dcf459845fd28f5a0d83d408a379b274ec5cc5</id>
<content type='text'>
commit ca1a47cd3f5f4c46ca188b1c9a27af87d1ab2216 upstream.

Patch series "mm/hugetlb: fixes for PMD table sharing (incl.  using
mmu_gather)", v3.

One functional fix, one performance regression fix, and two related
comment fixes.

I cleaned up my prototype I recently shared [1] for the performance fix,
deferring most of the cleanups I had in the prototype to a later point.
While doing that I identified the other things.

The goal of this patch set is to be backported to stable trees "fairly"
easily. At least patch #1 and #4.

Patch #1 fixes hugetlb_pmd_shared() not detecting any sharing
Patch #2 + #3 are simple comment fixes that patch #4 interacts with.
Patch #4 is a fix for the reported performance regression due to excessive
IPI broadcasts during fork()+exit().

The last patch is all about TLB flushes, IPIs and mmu_gather.
Read: complicated

There are plenty of cleanups in the future to be had + one reasonable
optimization on x86. But that's all out of scope for this series.

Runtime tested, with a focus on fixing the performance regression using
the original reproducer [2] on x86.


This patch (of 4):

We switched from (wrongly) using the page count to an independent shared
count.  Now, shared page tables have a refcount of 1 (excluding
speculative references) and instead use ptdesc-&gt;pt_share_count to identify
sharing.

We didn't convert hugetlb_pmd_shared(), so right now, we would never
detect a shared PMD table as such, because sharing/unsharing no longer
touches the refcount of a PMD table.

Page migration, like mbind() or migrate_pages() would allow for migrating
folios mapped into such shared PMD tables, even though the folios are not
exclusive.  In smaps we would account them as "private" although they are
"shared", and we would be wrongly setting the PM_MMAP_EXCLUSIVE in the
pagemap interface.

Fix it by properly using ptdesc_pmd_is_shared() in hugetlb_pmd_shared().

Link: https://lkml.kernel.org/r/20251223214037.580860-1-david@kernel.org
Link: https://lkml.kernel.org/r/20251223214037.580860-2-david@kernel.org
Link: https://lore.kernel.org/all/8cab934d-4a56-44aa-b641-bfd7e23bd673@kernel.org/ [1]
Link: https://lore.kernel.org/all/8cab934d-4a56-44aa-b641-bfd7e23bd673@kernel.org/ [2]
Fixes: 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count")
Signed-off-by: David Hildenbrand (Red Hat) &lt;david@kernel.org&gt;
Reviewed-by: Rik van Riel &lt;riel@surriel.com&gt;
Reviewed-by: Lance Yang &lt;lance.yang@linux.dev&gt;
Tested-by: Lance Yang &lt;lance.yang@linux.dev&gt;
Reviewed-by: Harry Yoo &lt;harry.yoo@oracle.com&gt;
Tested-by: Laurence Oberman &lt;loberman@redhat.com&gt;
Reviewed-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Acked-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Liu Shixin &lt;liushixin2@huawei.com&gt;
Cc: "Uschakow, Stanislav" &lt;suschako@amazon.de&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: David Hildenbrand (Arm) &lt;david@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>mm/hugetlb: fix copy_hugetlb_page_range() to use -&gt;pt_share_count</title>
<updated>2026-02-19T15:28:26+00:00</updated>
<author>
<name>Jane Chu</name>
<email>jane.chu@oracle.com</email>
</author>
<published>2025-09-16T00:45:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=8c9a1b0710510c3cc25526c815ca798705cb1936'/>
<id>urn:sha1:8c9a1b0710510c3cc25526c815ca798705cb1936</id>
<content type='text'>
commit 14967a9c7d247841b0312c48dcf8cd29e55a4cc8 upstream.

commit 59d9094df3d79 ("mm: hugetlb: independent PMD page table shared
count") introduced -&gt;pt_share_count dedicated to hugetlb PMD share count
tracking, but omitted fixing copy_hugetlb_page_range(), leaving the
function relying on page_count() for tracking that no longer works.

When lazy page table copy for hugetlb is disabled, that is, revert commit
bcd51a3c679d ("hugetlb: lazy page table copies in fork()") fork()'ing with
hugetlb PMD sharing quickly lockup -

[  239.446559] watchdog: BUG: soft lockup - CPU#75 stuck for 27s!
[  239.446611] RIP: 0010:native_queued_spin_lock_slowpath+0x7e/0x2e0
[  239.446631] Call Trace:
[  239.446633]  &lt;TASK&gt;
[  239.446636]  _raw_spin_lock+0x3f/0x60
[  239.446639]  copy_hugetlb_page_range+0x258/0xb50
[  239.446645]  copy_page_range+0x22b/0x2c0
[  239.446651]  dup_mmap+0x3e2/0x770
[  239.446654]  dup_mm.constprop.0+0x5e/0x230
[  239.446657]  copy_process+0xd17/0x1760
[  239.446660]  kernel_clone+0xc0/0x3e0
[  239.446661]  __do_sys_clone+0x65/0xa0
[  239.446664]  do_syscall_64+0x82/0x930
[  239.446668]  ? count_memcg_events+0xd2/0x190
[  239.446671]  ? syscall_trace_enter+0x14e/0x1f0
[  239.446676]  ? syscall_exit_work+0x118/0x150
[  239.446677]  ? arch_exit_to_user_mode_prepare.constprop.0+0x9/0xb0
[  239.446681]  ? clear_bhb_loop+0x30/0x80
[  239.446684]  ? clear_bhb_loop+0x30/0x80
[  239.446686]  entry_SYSCALL_64_after_hwframe+0x76/0x7e

There are two options to resolve the potential latent issue:
  1. warn against PMD sharing in copy_hugetlb_page_range(),
  2. fix it.
This patch opts for the second option.
While at it, simplify the comment, the details are not actually relevant
anymore.

Link: https://lkml.kernel.org/r/20250916004520.1604530-1-jane.chu@oracle.com
Fixes: 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count")
Signed-off-by: Jane Chu &lt;jane.chu@oracle.com&gt;
Reviewed-by: Harry Yoo &lt;harry.yoo@oracle.com&gt;
Acked-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Liu Shixin &lt;liushixin2@huawei.com&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: David Hildenbrand (Arm) &lt;david@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: add skb_header_pointer_careful() helper</title>
<updated>2026-02-11T12:39:14+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2026-01-28T14:15:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=fcbda653b5a888338ce7cdc186ec53edc260fe39'/>
<id>urn:sha1:fcbda653b5a888338ce7cdc186ec53edc260fe39</id>
<content type='text'>
[ Upstream commit 13e00fdc9236bd4d0bff4109d2983171fbcb74c4 ]

This variant of skb_header_pointer() should be used in contexts
where @offset argument is user-controlled and could be negative.

Negative offsets are supported, as long as the zone starts
between skb-&gt;head and skb-&gt;data.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Link: https://patch.msgid.link/20260128141539.3404400-2-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Stable-dep-of: cabd1a976375 ("net/sched: cls_u32: use skb_header_pointer_careful()")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>ptr_ring: do not block hard interrupts in ptr_ring_resize_multiple()</title>
<updated>2026-02-06T15:48:29+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2026-02-04T11:55:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=572777a258c048e0d0fb3a0c47430eadcefe80c0'/>
<id>urn:sha1:572777a258c048e0d0fb3a0c47430eadcefe80c0</id>
<content type='text'>
[ Upstream commit a126061c80d5efb4baef4bcf346094139cd81df6 ]

Jakub added a lockdep_assert_no_hardirq() check in __page_pool_put_page()
to increase test coverage.

syzbot found a splat caused by hard irq blocking in
ptr_ring_resize_multiple() [1]

As current users of ptr_ring_resize_multiple() do not require
hard irqs being masked, replace it to only block BH.

Rename helpers to better reflect they are safe against BH only.

- ptr_ring_resize_multiple() to ptr_ring_resize_multiple_bh()
- skb_array_resize_multiple() to skb_array_resize_multiple_bh()

[1]

WARNING: CPU: 1 PID: 9150 at net/core/page_pool.c:709 __page_pool_put_page net/core/page_pool.c:709 [inline]
WARNING: CPU: 1 PID: 9150 at net/core/page_pool.c:709 page_pool_put_unrefed_netmem+0x157/0xa40 net/core/page_pool.c:780
Modules linked in:
CPU: 1 UID: 0 PID: 9150 Comm: syz.1.1052 Not tainted 6.11.0-rc3-syzkaller-00202-gf8669d7b5f5d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:__page_pool_put_page net/core/page_pool.c:709 [inline]
RIP: 0010:page_pool_put_unrefed_netmem+0x157/0xa40 net/core/page_pool.c:780
Code: 74 0e e8 7c aa fb f7 eb 43 e8 75 aa fb f7 eb 3c 65 8b 1d 38 a8 6a 76 31 ff 89 de e8 a3 ae fb f7 85 db 74 0b e8 5a aa fb f7 90 &lt;0f&gt; 0b 90 eb 1d 65 8b 1d 15 a8 6a 76 31 ff 89 de e8 84 ae fb f7 85
RSP: 0018:ffffc9000bda6b58 EFLAGS: 00010083
RAX: ffffffff8997e523 RBX: 0000000000000000 RCX: 0000000000040000
RDX: ffffc9000fbd0000 RSI: 0000000000001842 RDI: 0000000000001843
RBP: 0000000000000000 R08: ffffffff8997df2c R09: 1ffffd40003a000d
R10: dffffc0000000000 R11: fffff940003a000e R12: ffffea0001d00040
R13: ffff88802e8a4000 R14: dffffc0000000000 R15: 00000000ffffffff
FS:  00007fb7aaf716c0(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa15a0d4b72 CR3: 00000000561b0000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 &lt;TASK&gt;
 tun_ptr_free drivers/net/tun.c:617 [inline]
 __ptr_ring_swap_queue include/linux/ptr_ring.h:571 [inline]
 ptr_ring_resize_multiple_noprof include/linux/ptr_ring.h:643 [inline]
 tun_queue_resize drivers/net/tun.c:3694 [inline]
 tun_device_event+0xaaf/0x1080 drivers/net/tun.c:3714
 notifier_call_chain+0x19f/0x3e0 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2032 [inline]
 call_netdevice_notifiers net/core/dev.c:2046 [inline]
 dev_change_tx_queue_len+0x158/0x2a0 net/core/dev.c:9024
 do_setlink+0xff6/0x41f0 net/core/rtnetlink.c:2923
 rtnl_setlink+0x40d/0x5a0 net/core/rtnetlink.c:3201
 rtnetlink_rcv_msg+0x73f/0xcf0 net/core/rtnetlink.c:6647
 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2550

Fixes: ff4e538c8c3e ("page_pool: add a lockdep check for recycling in hardirq")
Reported-by: syzbot+f56a5c5eac2b28439810@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/671e10df.050a0220.2b8c0f.01cf.GAE@google.com/T/
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Acked-by: Jason Wang &lt;jasowang@redhat.com&gt;
Link: https://patch.msgid.link/20241217135121.326370-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
[ 2c321f3f70bc ("mm: change inlined allocation helpers to account at the call site")
  is not ported to Linux-6.6.y. So remove the suffix "_noprof". ]
Signed-off-by: Alva Lan &lt;alvalan9@foxmail.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>xsk: Fix race condition in AF_XDP generic RX path</title>
<updated>2026-02-06T15:48:29+00:00</updated>
<author>
<name>e.kubanski</name>
<email>e.kubanski@partner.samsung.com</email>
</author>
<published>2026-02-04T08:29:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=b6978c565ce33658543c637060852434b4248d30'/>
<id>urn:sha1:b6978c565ce33658543c637060852434b4248d30</id>
<content type='text'>
[ Upstream commit a1356ac7749cafc4e27aa62c0c4604b5dca4983e ]

Move rx_lock from xsk_socket to xsk_buff_pool.
Fix synchronization for shared umem mode in
generic RX path where multiple sockets share
single xsk_buff_pool.

RX queue is exclusive to xsk_socket, while FILL
queue can be shared between multiple sockets.
This could result in race condition where two
CPU cores access RX path of two different sockets
sharing the same umem.

Protect both queues by acquiring spinlock in shared
xsk_buff_pool.

Lock contention may be minimized in the future by some
per-thread FQ buffering.

It's safe and necessary to move spin_lock_bh(rx_lock)
after xsk_rcv_check():
* xs-&gt;pool and spinlock_init is synchronized by
  xsk_bind() -&gt; xsk_is_bound() memory barriers.
* xsk_rcv_check() may return true at the moment
  of xsk_release() or xsk_unbind_dev(),
  however this will not cause any data races or
  race conditions. xsk_unbind_dev() removes xdp
  socket from all maps and waits for completion
  of all outstanding rx operations. Packets in
  RX path will either complete safely or drop.

Signed-off-by: Eryk Kubanski &lt;e.kubanski@partner.samsung.com&gt;
Fixes: bf0bdd1343efb ("xdp: fix race on generic receive path")
Acked-by: Magnus Karlsson &lt;magnus.karlsson@intel.com&gt;
Link: https://patch.msgid.link/20250416101908.10919-1-e.kubanski@partner.samsung.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
[ Conflict is resolved when backporting this fix. ]
Signed-off-by: Jianqiang kang &lt;jianqkang@sina.cn&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>perf: sched: Fix perf crash with new is_user_task() helper</title>
<updated>2026-02-06T15:48:28+00:00</updated>
<author>
<name>Steven Rostedt</name>
<email>rostedt@goodmis.org</email>
</author>
<published>2026-02-03T20:27:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=d84a4836dc246b7dc244e46a08ff992956b68db0'/>
<id>urn:sha1:d84a4836dc246b7dc244e46a08ff992956b68db0</id>
<content type='text'>
[ Upstream commit 76ed27608f7dd235b727ebbb12163438c2fbb617 ]

In order to do a user space stacktrace the current task needs to be a user
task that has executed in user space. It use to be possible to test if a
task is a user task or not by simply checking the task_struct mm field. If
it was non NULL, it was a user task and if not it was a kernel task.

But things have changed over time, and some kernel tasks now have their
own mm field.

An idea was made to instead test PF_KTHREAD and two functions were used to
wrap this check in case it became more complex to test if a task was a
user task or not[1]. But this was rejected and the C code simply checked
the PF_KTHREAD directly.

It was later found that not all kernel threads set PF_KTHREAD. The io-uring
helpers instead set PF_USER_WORKER and this needed to be added as well.

But checking the flags is still not enough. There's a very small window
when a task exits that it frees its mm field and it is set back to NULL.
If perf were to trigger at this moment, the flags test would say its a
user space task but when perf would read the mm field it would crash with
at NULL pointer dereference.

Now there are flags that can be used to test if a task is exiting, but
they are set in areas that perf may still want to profile the user space
task (to see where it exited). The only real test is to check both the
flags and the mm field.

Instead of making this modification in every location, create a new
is_user_task() helper function that does all the tests needed to know if
it is safe to read the user space memory or not.

[1] https://lore.kernel.org/all/20250425204120.639530125@goodmis.org/

Fixes: 90942f9fac05 ("perf: Use current-&gt;flags &amp; PF_KTHREAD|PF_USER_WORKER instead of current-&gt;mm == NULL")
Closes: https://lore.kernel.org/all/0d877e6f-41a7-4724-875d-0b0a27b8a545@roeck-us.net/
Reported-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Tested-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260129102821.46484722@gandalf.local.home
[ Adjust context ]
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>nfc: nci: Fix race between rfkill and nci_unregister_device().</title>
<updated>2026-02-06T15:48:23+00:00</updated>
<author>
<name>Kuniyuki Iwashima</name>
<email>kuniyu@google.com</email>
</author>
<published>2026-01-27T04:03:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=546eba0b10989de9ccc7fd619e874a30561e2b88'/>
<id>urn:sha1:546eba0b10989de9ccc7fd619e874a30561e2b88</id>
<content type='text'>
[ Upstream commit d2492688bb9fed6ab6e313682c387ae71a66ebae ]

syzbot reported the splat below [0] without a repro.

It indicates that struct nci_dev.cmd_wq had been destroyed before
nci_close_device() was called via rfkill.

nci_dev.cmd_wq is only destroyed in nci_unregister_device(), which
(I think) was called from virtual_ncidev_close() when syzbot close()d
an fd of virtual_ncidev.

The problem is that nci_unregister_device() destroys nci_dev.cmd_wq
first and then calls nfc_unregister_device(), which removes the
device from rfkill by rfkill_unregister().

So, the device is still visible via rfkill even after nci_dev.cmd_wq
is destroyed.

Let's unregister the device from rfkill first in nci_unregister_device().

Note that we cannot call nfc_unregister_device() before
nci_close_device() because

  1) nfc_unregister_device() calls device_del() which frees
     all memory allocated by devm_kzalloc() and linked to
     ndev-&gt;conn_info_list

  2) nci_rx_work() could try to queue nci_conn_info to
     ndev-&gt;conn_info_list which could be leaked

Thus, nfc_unregister_device() is split into two functions so we
can remove rfkill interfaces only before nci_close_device().

[0]:
DEBUG_LOCKS_WARN_ON(1)
WARNING: kernel/locking/lockdep.c:238 at hlock_class kernel/locking/lockdep.c:238 [inline], CPU#0: syz.0.8675/6349
WARNING: kernel/locking/lockdep.c:238 at check_wait_context kernel/locking/lockdep.c:4854 [inline], CPU#0: syz.0.8675/6349
WARNING: kernel/locking/lockdep.c:238 at __lock_acquire+0x39d/0x2cf0 kernel/locking/lockdep.c:5187, CPU#0: syz.0.8675/6349
Modules linked in:
CPU: 0 UID: 0 PID: 6349 Comm: syz.0.8675 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
RIP: 0010:hlock_class kernel/locking/lockdep.c:238 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4854 [inline]
RIP: 0010:__lock_acquire+0x3a4/0x2cf0 kernel/locking/lockdep.c:5187
Code: 18 00 4c 8b 74 24 08 75 27 90 e8 17 f2 fc 02 85 c0 74 1c 83 3d 50 e0 4e 0e 00 75 13 48 8d 3d 43 f7 51 0e 48 c7 c6 8b 3a de 8d &lt;67&gt; 48 0f b9 3a 90 31 c0 0f b6 98 c4 00 00 00 41 8b 45 20 25 ff 1f
RSP: 0018:ffffc9000c767680 EFLAGS: 00010046
RAX: 0000000000000001 RBX: 0000000000040000 RCX: 0000000000080000
RDX: ffffc90013080000 RSI: ffffffff8dde3a8b RDI: ffffffff8ff24ca0
RBP: 0000000000000003 R08: ffffffff8fef35a3 R09: 1ffffffff1fde6b4
R10: dffffc0000000000 R11: fffffbfff1fde6b5 R12: 00000000000012a2
R13: ffff888030338ba8 R14: ffff888030338000 R15: ffff888030338b30
FS:  00007fa5995f66c0(0000) GS:ffff8881256f8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7e72f842d0 CR3: 00000000485a0000 CR4: 00000000003526f0
Call Trace:
 &lt;TASK&gt;
 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
 touch_wq_lockdep_map+0xcb/0x180 kernel/workqueue.c:3940
 __flush_workqueue+0x14b/0x14f0 kernel/workqueue.c:3982
 nci_close_device+0x302/0x630 net/nfc/nci/core.c:567
 nci_dev_down+0x3b/0x50 net/nfc/nci/core.c:639
 nfc_dev_down+0x152/0x290 net/nfc/core.c:161
 nfc_rfkill_set_block+0x2d/0x100 net/nfc/core.c:179
 rfkill_set_block+0x1d2/0x440 net/rfkill/core.c:346
 rfkill_fop_write+0x461/0x5a0 net/rfkill/core.c:1301
 vfs_write+0x29a/0xb90 fs/read_write.c:684
 ksys_write+0x150/0x270 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa59b39acb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 &lt;48&gt; 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa5995f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fa59b615fa0 RCX: 00007fa59b39acb9
RDX: 0000000000000008 RSI: 0000200000000080 RDI: 0000000000000007
RBP: 00007fa59b408bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa59b616038 R14: 00007fa59b615fa0 R15: 00007ffc82218788
 &lt;/TASK&gt;

Fixes: 6a2968aaf50c ("NFC: basic NCI protocol implementation")
Reported-by: syzbot+f9c5fd1a0874f9069dce@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/695e7f56.050a0220.1c677c.036c.GAE@google.com/
Signed-off-by: Kuniyuki Iwashima &lt;kuniyu@google.com&gt;
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Link: https://patch.msgid.link/20260127040411.494931-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>bonding: annotate data-races around slave-&gt;last_rx</title>
<updated>2026-02-06T15:48:22+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2026-01-22T16:29:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=8c0be3277e7aefb2f900fc37ca3fe7df362e26f5'/>
<id>urn:sha1:8c0be3277e7aefb2f900fc37ca3fe7df362e26f5</id>
<content type='text'>
[ Upstream commit f6c3665b6dc53c3ab7d31b585446a953a74340ef ]

slave-&gt;last_rx and slave-&gt;target_last_arp_rx[...] can be read and written
locklessly. Add READ_ONCE() and WRITE_ONCE() annotations.

syzbot reported:

BUG: KCSAN: data-race in bond_rcv_validate / bond_rcv_validate

write to 0xffff888149f0d428 of 8 bytes by interrupt on cpu 1:
  bond_rcv_validate+0x202/0x7a0 drivers/net/bonding/bond_main.c:3335
  bond_handle_frame+0xde/0x5e0 drivers/net/bonding/bond_main.c:1533
  __netif_receive_skb_core+0x5b1/0x1950 net/core/dev.c:6039
  __netif_receive_skb_one_core net/core/dev.c:6150 [inline]
  __netif_receive_skb+0x59/0x270 net/core/dev.c:6265
  netif_receive_skb_internal net/core/dev.c:6351 [inline]
  netif_receive_skb+0x4b/0x2d0 net/core/dev.c:6410
...

write to 0xffff888149f0d428 of 8 bytes by interrupt on cpu 0:
  bond_rcv_validate+0x202/0x7a0 drivers/net/bonding/bond_main.c:3335
  bond_handle_frame+0xde/0x5e0 drivers/net/bonding/bond_main.c:1533
  __netif_receive_skb_core+0x5b1/0x1950 net/core/dev.c:6039
  __netif_receive_skb_one_core net/core/dev.c:6150 [inline]
  __netif_receive_skb+0x59/0x270 net/core/dev.c:6265
  netif_receive_skb_internal net/core/dev.c:6351 [inline]
  netif_receive_skb+0x4b/0x2d0 net/core/dev.c:6410
  br_netif_receive_skb net/bridge/br_input.c:30 [inline]
  NF_HOOK include/linux/netfilter.h:318 [inline]
...

value changed: 0x0000000100005365 -&gt; 0x0000000100005366

Fixes: f5b2b966f032 ("[PATCH] bonding: Validate probe replies in ARP monitor")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reported-by: syzbot &lt;syzkaller@googlegroups.com&gt;
Link: https://patch.msgid.link/20260122162914.2299312-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
</feed>
