From 14ade6ba4120fb38fcb5033998882c5b3d591194 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Tue, 14 Feb 2023 10:57:40 -0500 Subject: net: msg_zerocopy: elide page accounting if RLIM_INFINITY MSG_ZEROCOPY ensures that pinned user pages do not exceed the limit. If no limit is set, skip this accounting as otherwise expensive atomic_long operations are called for no reason. This accounting is already skipped for privileged (CAP_IPC_LOCK) users. Rely on the same mechanism: if no mmp->user is set, mm_unaccount_pinned_pages does not decrement either. Tested by running tools/testing/selftests/net/msg_zerocopy.sh with an unprivileged user for the TXMODE binary: ip netns exec "${NS1}" sudo -u "{$USER}" "${BIN}" "-${IP}" ... Signed-off-by: Willem de Bruijn Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20230214155740.3448763-1-willemdebruijn.kernel@gmail.com Signed-off-by: Jakub Kicinski --- net/core/skbuff.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'net') diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 13ea10cf8544..98ebce9f6a51 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1406,14 +1406,18 @@ EXPORT_SYMBOL_GPL(skb_morph); int mm_account_pinned_pages(struct mmpin *mmp, size_t size) { - unsigned long max_pg, num_pg, new_pg, old_pg; + unsigned long max_pg, num_pg, new_pg, old_pg, rlim; struct user_struct *user; if (capable(CAP_IPC_LOCK) || !size) return 0; + rlim = rlimit(RLIMIT_MEMLOCK); + if (rlim == RLIM_INFINITY) + return 0; + num_pg = (size >> PAGE_SHIFT) + 2; /* worst case */ - max_pg = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; + max_pg = rlim >> PAGE_SHIFT; user = mmp->user ? : current_user(); old_pg = atomic_long_read(&user->locked_vm); -- cgit v1.2.3