linux-stable.git/net/core/skbuff.c, branch linux-6.11.y

net: skbuff: sprinkle more __GFP_NOWARN on ingress allocs

2024-10-10T10:03:12+00:00

[ Upstream commit c89cca307b20917da739567a255a68a0798ee129 ]

build_skb() and frag allocations done with GFP_ATOMIC will
fail in real life, when system is under memory pressure,
and there's nothing we can do about that. So no point
printing warnings.

Signed-off-by: Jakub Kicinski 
Reviewed-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

page_pool: convert to use netmem

2024-07-03T01:59:33+00:00

Abstract the memory type from the page_pool so we can later add support
for new memory types. Convert the page_pool to use the new netmem type
abstraction, rather than use struct page directly.

As of this patch the netmem type is a no-op abstraction: it's always a
struct page underneath. All the page pool internals are converted to
use struct netmem instead of struct page, and the page pool now exports
2 APIs:

1. The existing struct page API.
2. The new struct netmem API.

Keeping the existing API is transitional; we do not want to refactor all
the current drivers using the page pool at once.

The netmem abstraction is currently a no-op. The page_pool uses
page_to_netmem() to convert allocated pages to netmem, and uses
netmem_to_page() to convert the netmem back to pages to pass to mm APIs,

Follow up patches to this series add non-paged netmem support to the
page_pool. This change is factored out on its own to limit the code
churn to this 1 patch, for ease of code review.

Signed-off-by: Mina Almasry 
Reviewed-by: Pavel Begunkov 
Link: https://patch.msgid.link/20240628003253.1694510-6-almasrymina@google.com
Signed-off-by: Jakub Kicinski

net: limit scope of a skb_zerocopy_iter_stream var

2024-07-02T10:06:50+00:00

skb_zerocopy_iter_stream() only uses @orig_uarg in the !link_skb path,
and we can move the local variable in the appropriate block.

Signed-off-by: Pavel Begunkov 
Reviewed-by: Willem de Bruijn 
Reviewed-by: Jens Axboe 
Signed-off-by: Paolo Abeni

net: always try to set ubuf in skb_zerocopy_iter_stream

2024-07-02T10:06:50+00:00

skb_zcopy_set() does nothing if there is already a ubuf_info associated
with an skb, and since ->link_skb should have set it several lines above
the check here essentially does nothing and can be removed. It's also
safer this way, because even if the callback is faulty we'll
have it set.

Signed-off-by: Pavel Begunkov 
Reviewed-by: Willem de Bruijn 
Reviewed-by: Jens Axboe 
Signed-off-by: Paolo Abeni

net: Use nested-BH locking for napi_alloc_cache.

2024-06-24T23:41:22+00:00

napi_alloc_cache is a per-CPU variable and relies on disabled BH for its
locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT
this data structure requires explicit locking.

Add a local_lock_t to the data structure and use local_lock_nested_bh()
for locking. This change adds only lockdep coverage and does not alter
the functional behaviour for !PREEMPT_RT.

Signed-off-by: Sebastian Andrzej Siewior 
Link: https://patch.msgid.link/20240620132727.660738-5-bigeasy@linutronix.de
Signed-off-by: Jakub Kicinski

net: Use __napi_alloc_frag_align() instead of open coding it.

2024-06-24T23:41:22+00:00

The else condition within __netdev_alloc_frag_align() is an open coded
__napi_alloc_frag_align().

Use __napi_alloc_frag_align() instead of open coding it.
Move fragsz assignment before page_frag_alloc_align() invocation because
__napi_alloc_frag_align() also contains this statement.

Signed-off-by: Sebastian Andrzej Siewior 
Link: https://patch.msgid.link/20240620132727.660738-4-bigeasy@linutronix.de
Signed-off-by: Jakub Kicinski

net: introduce sk_skb_reason_drop function

2024-06-19T11:44:22+00:00

Long used destructors kfree_skb and kfree_skb_reason do not pass
receiving socket to packet drop tracepoints trace_kfree_skb.
This makes it hard to track packet drops of a certain netns (container)
or a socket (user application).

The naming of these destructors are also not consistent with most sk/skb
operating functions, i.e. functions named "sk_xxx" or "skb_xxx".
Introduce a new functions sk_skb_reason_drop as drop-in replacement for
kfree_skb_reason on local receiving path. Callers can now pass receiving
sockets to the tracepoints.

kfree_skb and kfree_skb_reason are still usable but they are now just
inline helpers that call sk_skb_reason_drop.

Note it is not feasible to do the same to consume_skb. Packets not
dropped can flow through multiple receive handlers, and have multiple
receiving sockets. Leave it untouched for now.

Suggested-by: Eric Dumazet 
Signed-off-by: Yan Zhai 
Acked-by: Jesper Dangaard Brouer 
Signed-off-by: David S. Miller

net: add rx_sk to trace_kfree_skb

2024-06-19T11:44:22+00:00

skb does not include enough information to find out receiving
sockets/services and netns/containers on packet drops. In theory
skb->dev tells about netns, but it can get cleared/reused, e.g. by TCP
stack for OOO packet lookup. Similarly, skb->sk often identifies a local
sender, and tells nothing about a receiver.

Allow passing an extra receiving socket to the tracepoint to improve
the visibility on receiving drops.

Signed-off-by: Yan Zhai 
Acked-by: Jesper Dangaard Brouer 
Signed-off-by: David S. Miller

net: skb: add compatibility warnings to skb_shift()

2024-06-04T11:23:30+00:00

According to current semantics we should never try to shift data
between skbs which differ on decrypted or pp_recycle status.

Signed-off-by: Jakub Kicinski 
Reviewed-by: Eric Dumazet 
Reviewed-by: Willem de Bruijn 
Signed-off-by: Paolo Abeni

Revert "net: mirror skb frag ref/unref helpers"

2024-05-03T23:05:53+00:00

This reverts commit a580ea994fd37f4105028f5a85c38ff6508a2b25.

This revert is to resolve Dragos's report of page_pool leak here:
https://lore.kernel.org/lkml/20240424165646.1625690-2-dtatulea@nvidia.com/

The reverted patch interacts very badly with commit 2cc3aeb5eccc ("skbuff:
Fix a potential race while recycling page_pool packets"). The reverted
commit hopes that the pp_recycle + is_pp_page variables do not change
between the skb_frag_ref and skb_frag_unref operation. If such a change
occurs, the skb_frag_ref/unref will not operate on the same reference type.
In the case of Dragos's report, the grabbed ref was a pp ref, but the unref
was a page ref, because the pp_recycle setting on the skb was changed.

Attempting to fix this issue on the fly is risky. Lets revert and I hope
to reland this with better understanding and testing to ensure we don't
regress some edge case while streamlining skb reffing.

Fixes: a580ea994fd3 ("net: mirror skb frag ref/unref helpers")
Reported-by: Dragos Tatulea 
Signed-off-by: Mina Almasry 
Link: https://lore.kernel.org/r/20240502175423.2456544-1-almasrymina@google.com
Signed-off-by: Jakub Kicinski