linux-stable.git/include, branch v6.13.5

sched: Compact RSEQ concurrency IDs with reduced threads and affinity

2025-02-27T12:34:18+00:00

[ Upstream commit 02d954c0fdf91845169cdacc7405b120f90afe01 ]

When a process reduces its number of threads or clears bits in its CPU
affinity mask, the mm_cid allocation should eventually converge towards
smaller values.

However, the change introduced by:

commit 7e019dcc470f ("sched: Improve cache locality of RSEQ concurrency
IDs for intermittent workloads")

adds a per-mm/CPU recent_cid which is never unset unless a thread
migrates.

This is a tradeoff between:

A) Preserving cache locality after a transition from many threads to few
   threads, or after reducing the hamming weight of the allowed CPU mask.

B) Making the mm_cid upper bounds wrt nr threads and allowed CPU mask
   easy to document and understand.

C) Allowing applications to eventually react to mm_cid compaction after
   reduction of the nr threads or allowed CPU mask, making the tracking
   of mm_cid compaction easier by shrinking it back towards 0 or not.

D) Making sure applications that periodically reduce and then increase
   again the nr threads or allowed CPU mask still benefit from good
   cache locality with mm_cid.

Introduce the following changes:

* After shrinking the number of threads or reducing the number of
  allowed CPUs, reduce the value of max_nr_cid so expansion of CID
  allocation will preserve cache locality if the number of threads or
  allowed CPUs increase again.

* Only re-use a recent_cid if it is within the max_nr_cid upper bound,
  else find the first available CID.

Fixes: 7e019dcc470f ("sched: Improve cache locality of RSEQ concurrency IDs for intermittent workloads")
Signed-off-by: Mathieu Desnoyers 
Signed-off-by: Gabriele Monaco 
Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Gabriele Monaco 
Link: https://lkml.kernel.org/r/20250210153253.460471-2-gmonaco@redhat.com
Signed-off-by: Sasha Levin

net: allow small head cache usage with large MAX_SKB_FRAGS values

2025-02-27T12:34:15+00:00

[ Upstream commit 14ad6ed30a10afbe91b0749d6378285f4225d482 ]

Sabrina reported the following splat:

    WARNING: CPU: 0 PID: 1 at net/core/dev.c:6935 netif_napi_add_weight_locked+0x8f2/0xba0
    Modules linked in:
    CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.14.0-rc1-net-00092-g011b03359038 #996
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014
    RIP: 0010:netif_napi_add_weight_locked+0x8f2/0xba0
    Code: e8 c3 e6 6a fe 48 83 c4 28 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc c7 44 24 10 ff ff ff ff e9 8f fb ff ff e8 9e e6 6a fe <0f> 0b e9 d3 fe ff ff e8 92 e6 6a fe 48 8b 04 24 be ff ff ff ff 48
    RSP: 0000:ffffc9000001fc60 EFLAGS: 00010293
    RAX: 0000000000000000 RBX: ffff88806ce48128 RCX: 1ffff11001664b9e
    RDX: ffff888008f00040 RSI: ffffffff8317ca42 RDI: ffff88800b325cb6
    RBP: ffff88800b325c40 R08: 0000000000000001 R09: ffffed100167502c
    R10: ffff88800b3a8163 R11: 0000000000000000 R12: ffff88800ac1c168
    R13: ffff88800ac1c168 R14: ffff88800ac1c168 R15: 0000000000000007
    FS:  0000000000000000(0000) GS:ffff88806ce00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: ffff888008201000 CR3: 0000000004c94001 CR4: 0000000000370ef0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
    
    gro_cells_init+0x1ba/0x270
    xfrm_input_init+0x4b/0x2a0
    xfrm_init+0x38/0x50
    ip_rt_init+0x2d7/0x350
    ip_init+0xf/0x20
    inet_init+0x406/0x590
    do_one_initcall+0x9d/0x2e0
    do_initcalls+0x23b/0x280
    kernel_init_freeable+0x445/0x490
    kernel_init+0x20/0x1d0
    ret_from_fork+0x46/0x80
    ret_from_fork_asm+0x1a/0x30
    
    irq event stamp: 584330
    hardirqs last  enabled at (584338): [] __up_console_sem+0x77/0xb0
    hardirqs last disabled at (584345): [] __up_console_sem+0x5c/0xb0
    softirqs last  enabled at (583242): [] netlink_insert+0x14d/0x470
    softirqs last disabled at (583754): [] netif_napi_add_weight_locked+0x77d/0xba0

on kernel built with MAX_SKB_FRAGS=45, where SKB_WITH_OVERHEAD(1024)
is smaller than GRO_MAX_HEAD.

Such built additionally contains the revert of the single page frag cache
so that napi_get_frags() ends up using the page frag allocator, triggering
the splat.

Note that the underlying issue is independent from the mentioned
revert; address it ensuring that the small head cache will fit either TCP
and GRO allocation and updating napi_alloc_skb() and __netdev_alloc_skb()
to select kmalloc() usage for any allocation fitting such cache.

Reported-by: Sabrina Dubroca 
Suggested-by: Eric Dumazet 
Fixes: 3948b05950fd ("net: introduce a config option to tweak MAX_SKB_FRAGS")
Reviewed-by: Eric Dumazet 
Signed-off-by: Paolo Abeni 
Signed-off-by: Sasha Levin

tcp: drop secpath at the same time as we currently drop dst

2025-02-27T12:34:15+00:00

[ Upstream commit 9b6412e6979f6f9e0632075f8f008937b5cd4efd ]

Xiumei reported hitting the WARN in xfrm6_tunnel_net_exit while
running tests that boil down to:
- create a pair of netns
- run a basic TCP test over ipcomp6
- delete the pair of netns

The xfrm_state found on spi_byaddr was not deleted at the time we
delete the netns, because we still have a reference on it. This
lingering reference comes from a secpath (which holds a ref on the
xfrm_state), which is still attached to an skb. This skb is not
leaked, it ends up on sk_receive_queue and then gets defer-free'd by
skb_attempt_defer_free.

The problem happens when we defer freeing an skb (push it on one CPU's
defer_list), and don't flush that list before the netns is deleted. In
that case, we still have a reference on the xfrm_state that we don't
expect at this point.

We already drop the skb's dst in the TCP receive path when it's no
longer needed, so let's also drop the secpath. At this point,
tcp_filter has already called into the LSM hooks that may require the
secpath, so it should not be needed anymore. However, in some of those
places, the MPTCP extension has just been attached to the skb, so we
cannot simply drop all extensions.

Fixes: 68822bdf76f1 ("net: generalize skb freeing deferral to per-cpu lists")
Reported-by: Xiumei Mu
Signed-off-by: Sabrina Dubroca
Reviewed-by: Eric Dumazet
Link: https://patch.msgid.link/5055ba8f8f72bdcb602faa299faca73c280b7735.1739743613.git.sd@queasysnail.net
Signed-off-by: Paolo Abeni
Signed-off-by: Sasha Levin

net: Add non-RCU dev_getbyhwaddr() helper

2025-02-27T12:34:15+00:00

[ Upstream commit 4b5a28b38c4a0106c64416a1b2042405166b26ce ]

Add dedicated helper for finding devices by hardware address when
holding rtnl_lock, similar to existing dev_getbyhwaddr_rcu(). This prevents
PROVE_LOCKING warnings when rtnl_lock is held but RCU read lock is not.

Extract common address comparison logic into dev_addr_cmp().

The context about this change could be found in the following
discussion:

Link: https://lore.kernel.org/all/20250206-scarlet-ermine-of-improvement-1fcac5@leitao/

Cc: kuniyu@amazon.com
Cc: ushankar@purestorage.com
Suggested-by: Eric Dumazet 
Signed-off-by: Breno Leitao 
Reviewed-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20250218-arm_fix_selftest-v5-1-d3d6892db9e1@debian.org
Signed-off-by: Jakub Kicinski 
Stable-dep-of: 4eae0ee0f1e6 ("arp: switch to dev_getbyhwaddr() in arp_req_set_public()")
Signed-off-by: Sasha Levin

net: pse-pd: Use power limit at driver side instead of current limit

2025-02-27T12:34:14+00:00

[ Upstream commit e0a5e2bba38aa61a900934b45d6e846e0a6d7524 ]

The regulator framework uses current limits, but the PSE standard and
known PSE controllers rely on power limits. Instead of converting
current to power within each driver, perform the conversion in the PSE
core. This avoids redundancy in driver implementation and aligns better
with the standard, simplifying driver development.

Remove at the same time the _pse_ethtool_get_status() function which is
not needed anymore.

Acked-by: Oleksij Rempel 
Signed-off-by: Kory Maincent 
Signed-off-by: Paolo Abeni 
Stable-dep-of: f6093c5ec74d ("net: pse-pd: pd692x0: Fix power limit retrieval")
Signed-off-by: Sasha Levin

PCI: Remove devres from pci_intx()

2025-02-27T12:34:13+00:00

[ Upstream commit dfa2f4d5f9e5d757700cefa8ee480099889f1c69 ]

pci_intx() is a hybrid function which can sometimes be managed through
devres. This hybrid nature is undesirable.

Since all users of pci_intx() have by now been ported either to
always-managed pcim_intx() or never-managed pci_intx_unmanaged(), the
devres functionality can be removed from pci_intx().

Consequently, pci_intx_unmanaged() is now redundant, because pci_intx()
itself is now unmanaged.

Remove the devres functionality from pci_intx(). Have all users of
pci_intx_unmanaged() call pci_intx(). Remove pci_intx_unmanaged().

Link: https://lore.kernel.org/r/20241209130632.132074-13-pstanner@redhat.com
Signed-off-by: Philipp Stanner 
Signed-off-by: Bjorn Helgaas 
Acked-by: Paolo Abeni 
Stable-dep-of: d555ed45a5a1 ("PCI: Restore original INTX_DISABLE bit by pcim_intx()")
Signed-off-by: Sasha Levin

PCI: Export pci_intx_unmanaged() and pcim_intx()

2025-02-27T12:34:13+00:00

[ Upstream commit f546e8033d8f3e45d49622f04ca2fde650b80f6d ]

pci_intx() is a hybrid function which sometimes performs devres operations,
depending on whether pcim_enable_device() has been used to enable the
pci_dev. This sometimes-managed nature of the function is problematic.
Notably, it causes the function to allocate under some circumstances which
makes it unusable from interrupt context.

Export pcim_intx() (which is always managed) and rename __pcim_intx()
(which is never managed) to pci_intx_unmanaged() and export it as well.

Then all callers of pci_intx() can be ported to the version they need,
depending whether they use pci_enable_device() or pcim_enable_device().

Link: https://lore.kernel.org/r/20241209130632.132074-3-pstanner@redhat.com
Signed-off-by: Philipp Stanner 
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Damien Le Moal 
Stable-dep-of: d555ed45a5a1 ("PCI: Restore original INTX_DISABLE bit by pcim_intx()")
Signed-off-by: Sasha Levin

compiler.h: Move C string helpers into C-only kernel section

2025-02-21T13:11:15+00:00

[ Upstream commit cb7380de9e4cbc9a24216b722ec50e092ae83036 ]

The C kernel helpers for evaluating C Strings were positioned where they
were visible to assembly inclusion, which was not intended. Move them
into the kernel and C-only area of the header so future changes won't
confuse the assembler.

Fixes: d7a516c6eeae ("compiler.h: Fix undefined BUILD_BUG_ON_ZERO()")
Fixes: 559048d156ff ("string: Check for "nonstring" attribute on strscpy() arguments")
Reviewed-by: Miguel Ojeda 
Signed-off-by: Kees Cook 
Signed-off-by: Sasha Levin

net: add dev_net_rcu() helper

2025-02-21T13:11:14+00:00

[ Upstream commit 482ad2a4ace2740ca0ff1cbc8f3c7f862f3ab507 ]

dev->nd_net can change, readers should either
use rcu_read_lock() or RTNL.

We currently use a generic helper, dev_net() with
no debugging support. We probably have many hidden bugs.

Add dev_net_rcu() helper for callers using rcu_read_lock()
protection.

Signed-off-by: Eric Dumazet 
Reviewed-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20250205155120.1676781-2-edumazet@google.com
Signed-off-by: Jakub Kicinski 
Stable-dep-of: 71b8471c93fa ("ipv4: use RCU protection in ipv4_default_advmss()")
Signed-off-by: Sasha Levin

ipv4: use RCU protection in ip_dst_mtu_maybe_forward()

2025-02-21T13:11:14+00:00

[ Upstream commit 071d8012869b6af352acca346ade13e7be90a49f ]

ip_dst_mtu_maybe_forward() must use RCU protection to make
sure the net structure it reads does not disappear.

Fixes: f87c10a8aa1e8 ("ipv4: introduce ip_dst_mtu_maybe_forward and protect forwarding path against pmtu spoofing")
Signed-off-by: Eric Dumazet 
Reviewed-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20250205155120.1676781-4-edumazet@google.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin