From 173e7622ccb3f46834bd4176ed363f435e142942 Mon Sep 17 00:00:00 2001 From: Mina Almasry Date: Thu, 2 May 2024 10:54:22 -0700 Subject: [PATCH] Revert "net: mirror skb frag ref/unref helpers" 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 --- .../chelsio/inline_crypto/ch_ktls/chcr_ktls.c | 2 +- drivers/net/ethernet/sun/cassini.c | 4 +- drivers/net/veth.c | 2 +- include/linux/skbuff_ref.h | 39 ++-------------- net/core/skbuff.c | 46 +++++++++++++++++-- net/tls/tls_device_fallback.c | 2 +- 6 files changed, 51 insertions(+), 44 deletions(-) diff --git a/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c b/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c index 3832c2e8ea5a..e8e460a92e0e 100644 --- a/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c +++ b/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c @@ -1659,7 +1659,7 @@ static void chcr_ktls_copy_record_in_skb(struct sk_buff *nskb, for (i = 0; i < record->num_frags; i++) { skb_shinfo(nskb)->frags[i] = record->frags[i]; /* increase the frag ref count */ - __skb_frag_ref(&skb_shinfo(nskb)->frags[i], nskb->pp_recycle); + __skb_frag_ref(&skb_shinfo(nskb)->frags[i]); } skb_shinfo(nskb)->nr_frags = record->num_frags; diff --git a/drivers/net/ethernet/sun/cassini.c b/drivers/net/ethernet/sun/cassini.c index f058e154a3bc..8f1f43dbb76d 100644 --- a/drivers/net/ethernet/sun/cassini.c +++ b/drivers/net/ethernet/sun/cassini.c @@ -2000,7 +2000,7 @@ static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc, skb->len += hlen - swivel; skb_frag_fill_page_desc(frag, page->buffer, off, hlen - swivel); - __skb_frag_ref(frag, skb->pp_recycle); + __skb_frag_ref(frag); /* any more data? */ if ((words[0] & RX_COMP1_SPLIT_PKT) && ((dlen -= hlen) > 0)) { @@ -2024,7 +2024,7 @@ static int cas_rx_process_pkt(struct cas *cp, struct cas_rx_comp *rxc, frag++; skb_frag_fill_page_desc(frag, page->buffer, 0, hlen); - __skb_frag_ref(frag, skb->pp_recycle); + __skb_frag_ref(frag); RX_USED_ADD(page, hlen + cp->crc_size); } diff --git a/drivers/net/veth.c b/drivers/net/veth.c index 0b0293629329..426e68a95067 100644 --- a/drivers/net/veth.c +++ b/drivers/net/veth.c @@ -717,7 +717,7 @@ static void veth_xdp_get(struct xdp_buff *xdp) return; for (i = 0; i < sinfo->nr_frags; i++) - __skb_frag_ref(&sinfo->frags[i], false); + __skb_frag_ref(&sinfo->frags[i]); } static int veth_convert_skb_to_xdp_buff(struct veth_rq *rq, diff --git a/include/linux/skbuff_ref.h b/include/linux/skbuff_ref.h index 4dcdbe9fbc5f..11f0a4063403 100644 --- a/include/linux/skbuff_ref.h +++ b/include/linux/skbuff_ref.h @@ -8,47 +8,16 @@ #define _LINUX_SKBUFF_REF_H #include -#include - -#ifdef CONFIG_PAGE_POOL -static inline bool is_pp_page(struct page *page) -{ - return (page->pp_magic & ~0x3UL) == PP_SIGNATURE; -} - -static inline bool napi_pp_get_page(struct page *page) -{ - page = compound_head(page); - - if (!is_pp_page(page)) - return false; - - page_pool_ref_page(page); - return true; -} -#endif - -static inline void skb_page_ref(struct page *page, bool recycle) -{ -#ifdef CONFIG_PAGE_POOL - if (recycle && napi_pp_get_page(page)) - return; -#endif - get_page(page); -} /** * __skb_frag_ref - take an addition reference on a paged fragment. * @frag: the paged fragment - * @recycle: skb->pp_recycle param of the parent skb. False if no parent skb. * - * Takes an additional reference on the paged fragment @frag. Obtains the - * correct reference count depending on whether skb->pp_recycle is set and - * whether the frag is a page pool frag. + * Takes an additional reference on the paged fragment @frag. */ -static inline void __skb_frag_ref(skb_frag_t *frag, bool recycle) +static inline void __skb_frag_ref(skb_frag_t *frag) { - skb_page_ref(skb_frag_page(frag), recycle); + get_page(skb_frag_page(frag)); } /** @@ -60,7 +29,7 @@ static inline void __skb_frag_ref(skb_frag_t *frag, bool recycle) */ static inline void skb_frag_ref(struct sk_buff *skb, int f) { - __skb_frag_ref(&skb_shinfo(skb)->frags[f], skb->pp_recycle); + __skb_frag_ref(&skb_shinfo(skb)->frags[f]); } bool napi_pp_put_page(struct page *page); diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 28cd640a6ea9..466999a7515e 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -904,6 +904,11 @@ static void skb_clone_fraglist(struct sk_buff *skb) skb_get(list); } +static bool is_pp_page(struct page *page) +{ + return (page->pp_magic & ~0x3UL) == PP_SIGNATURE; +} + int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb, unsigned int headroom) { @@ -1025,6 +1030,37 @@ static bool skb_pp_recycle(struct sk_buff *skb, void *data) return napi_pp_put_page(virt_to_page(data)); } +/** + * skb_pp_frag_ref() - Increase fragment references of a page pool aware skb + * @skb: page pool aware skb + * + * Increase the fragment reference count (pp_ref_count) of a skb. This is + * intended to gain fragment references only for page pool aware skbs, + * i.e. when skb->pp_recycle is true, and not for fragments in a + * non-pp-recycling skb. It has a fallback to increase references on normal + * pages, as page pool aware skbs may also have normal page fragments. + */ +static int skb_pp_frag_ref(struct sk_buff *skb) +{ + struct skb_shared_info *shinfo; + struct page *head_page; + int i; + + if (!skb->pp_recycle) + return -EINVAL; + + shinfo = skb_shinfo(skb); + + for (i = 0; i < shinfo->nr_frags; i++) { + head_page = compound_head(skb_frag_page(&shinfo->frags[i])); + if (likely(is_pp_page(head_page))) + page_pool_ref_page(head_page); + else + page_ref_inc(head_page); + } + return 0; +} + static void skb_kfree_head(void *head, unsigned int end_offset) { if (end_offset == SKB_SMALL_HEAD_HEADROOM) @@ -4160,7 +4196,7 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen) to++; } else { - __skb_frag_ref(fragfrom, skb->pp_recycle); + __skb_frag_ref(fragfrom); skb_frag_page_copy(fragto, fragfrom); skb_frag_off_copy(fragto, fragfrom); skb_frag_size_set(fragto, todo); @@ -4810,7 +4846,7 @@ normal: } *nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag; - __skb_frag_ref(nskb_frag, nskb->pp_recycle); + __skb_frag_ref(nskb_frag); size = skb_frag_size(nskb_frag); if (pos < offset) { @@ -5941,8 +5977,10 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, /* if the skb is not cloned this does nothing * since we set nr_frags to 0. */ - for (i = 0; i < from_shinfo->nr_frags; i++) - __skb_frag_ref(&from_shinfo->frags[i], from->pp_recycle); + if (skb_pp_frag_ref(from)) { + for (i = 0; i < from_shinfo->nr_frags; i++) + __skb_frag_ref(&from_shinfo->frags[i]); + } to->truesize += delta; to->len += len; diff --git a/net/tls/tls_device_fallback.c b/net/tls/tls_device_fallback.c index 9237dded4467..f9e3d3d90dcf 100644 --- a/net/tls/tls_device_fallback.c +++ b/net/tls/tls_device_fallback.c @@ -278,7 +278,7 @@ static int fill_sg_in(struct scatterlist *sg_in, for (i = 0; remaining > 0; i++) { skb_frag_t *frag = &record->frags[i]; - __skb_frag_ref(frag, false); + __skb_frag_ref(frag); sg_set_page(sg_in + i, skb_frag_page(frag), skb_frag_size(frag), skb_frag_off(frag));