Merge branch '100GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue

Tony Nguyen says:

====================
ice: fix Rx data path for heavy 9k MTU traffic

Maciej Fijalkowski says:

This patchset fixes a pretty nasty issue that was reported by RedHat
folks which occurred after ~30 minutes (this value varied, just trying
here to state that it was not observed immediately but rather after a
considerable longer amount of time) when ice driver was tortured with
jumbo frames via mix of iperf traffic executed simultaneously with
wrk/nginx on client/server sides (HTTP and TCP workloads basically).

The reported splats were spanning across all the bad things that can
happen to the state of page - refcount underflow, use-after-free, etc.
One of these looked as follows:

[ 2084.019891] BUG: Bad page state in process swapper/34  pfn:97fcd0
[ 2084.025990] page:00000000a60ee772 refcount:-1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x97fcd0
[ 2084.035462] flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff)
[ 2084.041990] raw: 0017ffffc0000000 dead000000000100 dead000000000122 0000000000000000
[ 2084.049730] raw: 0000000000000000 0000000000000000 ffffffffffffffff 0000000000000000
[ 2084.057468] page dumped because: nonzero _refcount
[ 2084.062260] Modules linked in: bonding tls sunrpc intel_rapl_msr intel_rapl_common intel_uncore_frequency intel_uncore_frequency_common i10nm_edac nfit libnvdimm x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm mgag200 irqd
[ 2084.137829] CPU: 34 PID: 0 Comm: swapper/34 Kdump: loaded Not tainted 5.14.0-427.37.1.el9_4.x86_64 #1
[ 2084.147039] Hardware name: Dell Inc. PowerEdge R750/0216NK, BIOS 1.13.2 12/19/2023
[ 2084.154604] Call Trace:
[ 2084.157058]  <IRQ>
[ 2084.159080]  dump_stack_lvl+0x34/0x48
[ 2084.162752]  bad_page.cold+0x63/0x94
[ 2084.166333]  check_new_pages+0xb3/0xe0
[ 2084.170083]  rmqueue_bulk+0x2d2/0x9e0
[ 2084.173749]  ? ktime_get+0x35/0xa0
[ 2084.177159]  rmqueue_pcplist+0x13b/0x210
[ 2084.181081]  rmqueue+0x7d3/0xd40
[ 2084.184316]  ? xas_load+0x9/0xa0
[ 2084.187547]  ? xas_find+0x183/0x1d0
[ 2084.191041]  ? xa_find_after+0xd0/0x130
[ 2084.194879]  ? intel_iommu_iotlb_sync_map+0x89/0xe0
[ 2084.199759]  get_page_from_freelist+0x11f/0x530
[ 2084.204291]  __alloc_pages+0xf2/0x250
[ 2084.207958]  ice_alloc_rx_bufs+0xcc/0x1c0 [ice]
[ 2084.212543]  ice_clean_rx_irq+0x631/0xa20 [ice]
[ 2084.217111]  ice_napi_poll+0xdf/0x2a0 [ice]
[ 2084.221330]  __napi_poll+0x27/0x170
[ 2084.224824]  net_rx_action+0x233/0x2f0
[ 2084.228575]  __do_softirq+0xc7/0x2ac
[ 2084.232155]  __irq_exit_rcu+0xa1/0xc0
[ 2084.235821]  common_interrupt+0x80/0xa0
[ 2084.239662]  </IRQ>
[ 2084.241768]  <TASK>

The fix is mostly about reverting what was done in commit 1dc1a7e
("ice: Centrallize Rx buffer recycling") followed by proper timing on
page_count() storage and then removing the ice_rx_buf::act related logic
(which was mostly introduced for purposes from cited commit).

Special thanks to Xu Du for providing reproducer and Jacob Keller for
initial extensive analysis.

* '100GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue:
  ice: stop storing XDP verdict within ice_rx_buf
  ice: gather page_count()'s of each frag right before XDP prog call
  ice: put Rx buffers after being done with current frame
====================

Link: https://patch.msgid.link/20250131185415.3741532-1-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

drivers/net/ethernet/intel/ice/ice_txrx.c

@@ -527,15 +527,14 @@ int ice_setup_rx_ring(struct ice_rx_ring *rx_ring)
  * @xdp: xdp_buff used as input to the XDP program
  * @xdp_prog: XDP program to run
  * @xdp_ring: ring to be used for XDP_TX action
- * @rx_buf: Rx buffer to store the XDP action
  * @eop_desc: Last descriptor in packet to read metadata from
  *
  * Returns any of ICE_XDP_{PASS, CONSUMED, TX, REDIR}
  */
-static void
+static u32
 ice_run_xdp(struct ice_rx_ring *rx_ring, struct xdp_buff *xdp,
 	    struct bpf_prog *xdp_prog, struct ice_tx_ring *xdp_ring,
-	    struct ice_rx_buf *rx_buf, union ice_32b_rx_flex_desc *eop_desc)
+	    union ice_32b_rx_flex_desc *eop_desc)
 {
 	unsigned int ret = ICE_XDP_PASS;
 	u32 act;
@@ -574,7 +573,7 @@ ice_run_xdp(struct ice_rx_ring *rx_ring, struct xdp_buff *xdp,
 		ret = ICE_XDP_CONSUMED;
 	}
 exit:
-	ice_set_rx_bufs_act(xdp, rx_ring, ret);
+	return ret;
 }
 
 /**
@@ -860,10 +859,8 @@ ice_add_xdp_frag(struct ice_rx_ring *rx_ring, struct xdp_buff *xdp,
 		xdp_buff_set_frags_flag(xdp);
 	}
 
-	if (unlikely(sinfo->nr_frags == MAX_SKB_FRAGS)) {
-		ice_set_rx_bufs_act(xdp, rx_ring, ICE_XDP_CONSUMED);
+	if (unlikely(sinfo->nr_frags == MAX_SKB_FRAGS))
 		return -ENOMEM;
-	}
 
 	__skb_fill_page_desc_noacc(sinfo, sinfo->nr_frags++, rx_buf->page,
 				   rx_buf->page_offset, size);
@@ -924,7 +921,6 @@ ice_get_rx_buf(struct ice_rx_ring *rx_ring, const unsigned int size,
 	struct ice_rx_buf *rx_buf;
 
 	rx_buf = &rx_ring->rx_buf[ntc];
-	rx_buf->pgcnt = page_count(rx_buf->page);
 	prefetchw(rx_buf->page);
 
 	if (!size)
@@ -940,6 +936,31 @@ ice_get_rx_buf(struct ice_rx_ring *rx_ring, const unsigned int size,
 	return rx_buf;
 }
 
+/**
+ * ice_get_pgcnts - grab page_count() for gathered fragments
+ * @rx_ring: Rx descriptor ring to store the page counts on
+ *
+ * This function is intended to be called right before running XDP
+ * program so that the page recycling mechanism will be able to take
+ * a correct decision regarding underlying pages; this is done in such
+ * way as XDP program can change the refcount of page
+ */
+static void ice_get_pgcnts(struct ice_rx_ring *rx_ring)
+{
+	u32 nr_frags = rx_ring->nr_frags + 1;
+	u32 idx = rx_ring->first_desc;
+	struct ice_rx_buf *rx_buf;
+	u32 cnt = rx_ring->count;
+
+	for (int i = 0; i < nr_frags; i++) {
+		rx_buf = &rx_ring->rx_buf[idx];
+		rx_buf->pgcnt = page_count(rx_buf->page);
+
+		if (++idx == cnt)
+			idx = 0;
+	}
+}
+
 /**
  * ice_build_skb - Build skb around an existing buffer
  * @rx_ring: Rx descriptor ring to transact packets on
@@ -1051,12 +1072,12 @@ ice_construct_skb(struct ice_rx_ring *rx_ring, struct xdp_buff *xdp)
 				rx_buf->page_offset + headlen, size,
 				xdp->frame_sz);
 	} else {
-		/* buffer is unused, change the act that should be taken later
-		 * on; data was copied onto skb's linear part so there's no
+		/* buffer is unused, restore biased page count in Rx buffer;
+		 * data was copied onto skb's linear part so there's no
 		 * need for adjusting page offset and we can reuse this buffer
 		 * as-is
 		 */
-		rx_buf->act = ICE_SKB_CONSUMED;
+		rx_buf->pagecnt_bias++;
 	}
 
 	if (unlikely(xdp_buff_has_frags(xdp))) {
@@ -1103,6 +1124,65 @@ ice_put_rx_buf(struct ice_rx_ring *rx_ring, struct ice_rx_buf *rx_buf)
 	rx_buf->page = NULL;
 }
 
+/**
+ * ice_put_rx_mbuf - ice_put_rx_buf() caller, for all frame frags
+ * @rx_ring: Rx ring with all the auxiliary data
+ * @xdp: XDP buffer carrying linear + frags part
+ * @xdp_xmit: XDP_TX/XDP_REDIRECT verdict storage
+ * @ntc: a current next_to_clean value to be stored at rx_ring
+ * @verdict: return code from XDP program execution
+ *
+ * Walk through gathered fragments and satisfy internal page
+ * recycle mechanism; we take here an action related to verdict
+ * returned by XDP program;
+ */
+static void ice_put_rx_mbuf(struct ice_rx_ring *rx_ring, struct xdp_buff *xdp,
+			    u32 *xdp_xmit, u32 ntc, u32 verdict)
+{
+	u32 nr_frags = rx_ring->nr_frags + 1;
+	u32 idx = rx_ring->first_desc;
+	u32 cnt = rx_ring->count;
+	u32 post_xdp_frags = 1;
+	struct ice_rx_buf *buf;
+	int i;
+
+	if (unlikely(xdp_buff_has_frags(xdp)))
+		post_xdp_frags += xdp_get_shared_info_from_buff(xdp)->nr_frags;
+
+	for (i = 0; i < post_xdp_frags; i++) {
+		buf = &rx_ring->rx_buf[idx];
+
+		if (verdict & (ICE_XDP_TX | ICE_XDP_REDIR)) {
+			ice_rx_buf_adjust_pg_offset(buf, xdp->frame_sz);
+			*xdp_xmit |= verdict;
+		} else if (verdict & ICE_XDP_CONSUMED) {
+			buf->pagecnt_bias++;
+		} else if (verdict == ICE_XDP_PASS) {
+			ice_rx_buf_adjust_pg_offset(buf, xdp->frame_sz);
+		}
+
+		ice_put_rx_buf(rx_ring, buf);
+
+		if (++idx == cnt)
+			idx = 0;
+	}
+	/* handle buffers that represented frags released by XDP prog;
+	 * for these we keep pagecnt_bias as-is; refcount from struct page
+	 * has been decremented within XDP prog and we do not have to increase
+	 * the biased refcnt
+	 */
+	for (; i < nr_frags; i++) {
+		buf = &rx_ring->rx_buf[idx];
+		ice_put_rx_buf(rx_ring, buf);
+		if (++idx == cnt)
+			idx = 0;
+	}
+
+	xdp->data = NULL;
+	rx_ring->first_desc = ntc;
+	rx_ring->nr_frags = 0;
+}
+
 /**
  * ice_clean_rx_irq - Clean completed descriptors from Rx ring - bounce buf
  * @rx_ring: Rx descriptor ring to transact packets on
@@ -1120,15 +1200,13 @@ int ice_clean_rx_irq(struct ice_rx_ring *rx_ring, int budget)
 	unsigned int total_rx_bytes = 0, total_rx_pkts = 0;
 	unsigned int offset = rx_ring->rx_offset;
 	struct xdp_buff *xdp = &rx_ring->xdp;
-	u32 cached_ntc = rx_ring->first_desc;
 	struct ice_tx_ring *xdp_ring = NULL;
 	struct bpf_prog *xdp_prog = NULL;
 	u32 ntc = rx_ring->next_to_clean;
+	u32 cached_ntu, xdp_verdict;
 	u32 cnt = rx_ring->count;
 	u32 xdp_xmit = 0;
-	u32 cached_ntu;
 	bool failure;
-	u32 first;
 
 	xdp_prog = READ_ONCE(rx_ring->xdp_prog);
 	if (xdp_prog) {
@@ -1190,6 +1268,7 @@ int ice_clean_rx_irq(struct ice_rx_ring *rx_ring, int budget)
 			xdp_prepare_buff(xdp, hard_start, offset, size, !!offset);
 			xdp_buff_clear_frags_flag(xdp);
 		} else if (ice_add_xdp_frag(rx_ring, xdp, rx_buf, size)) {
+			ice_put_rx_mbuf(rx_ring, xdp, NULL, ntc, ICE_XDP_CONSUMED);
 			break;
 		}
 		if (++ntc == cnt)
@@ -1199,15 +1278,15 @@ int ice_clean_rx_irq(struct ice_rx_ring *rx_ring, int budget)
 		if (ice_is_non_eop(rx_ring, rx_desc))
 			continue;
 
-		ice_run_xdp(rx_ring, xdp, xdp_prog, xdp_ring, rx_buf, rx_desc);
-		if (rx_buf->act == ICE_XDP_PASS)
+		ice_get_pgcnts(rx_ring);
+		xdp_verdict = ice_run_xdp(rx_ring, xdp, xdp_prog, xdp_ring, rx_desc);
+		if (xdp_verdict == ICE_XDP_PASS)
 			goto construct_skb;
 		total_rx_bytes += xdp_get_buff_len(xdp);
 		total_rx_pkts++;
 
-		xdp->data = NULL;
-		rx_ring->first_desc = ntc;
-		rx_ring->nr_frags = 0;
+		ice_put_rx_mbuf(rx_ring, xdp, &xdp_xmit, ntc, xdp_verdict);
+
 		continue;
 construct_skb:
 		if (likely(ice_ring_uses_build_skb(rx_ring)))
@@ -1217,18 +1296,12 @@ int ice_clean_rx_irq(struct ice_rx_ring *rx_ring, int budget)
 		/* exit if we failed to retrieve a buffer */
 		if (!skb) {
 			rx_ring->ring_stats->rx_stats.alloc_page_failed++;
-			rx_buf->act = ICE_XDP_CONSUMED;
-			if (unlikely(xdp_buff_has_frags(xdp)))
-				ice_set_rx_bufs_act(xdp, rx_ring,
-						    ICE_XDP_CONSUMED);
-			xdp->data = NULL;
-			rx_ring->first_desc = ntc;
-			rx_ring->nr_frags = 0;
-			break;
+			xdp_verdict = ICE_XDP_CONSUMED;
 		}
-		xdp->data = NULL;
-		rx_ring->first_desc = ntc;
-		rx_ring->nr_frags = 0;
+		ice_put_rx_mbuf(rx_ring, xdp, &xdp_xmit, ntc, xdp_verdict);
+
+		if (!skb)
+			break;
 
 		stat_err_bits = BIT(ICE_RX_FLEX_DESC_STATUS0_RXE_S);
 		if (unlikely(ice_test_staterr(rx_desc->wb.status_error0,
@@ -1257,23 +1330,6 @@ int ice_clean_rx_irq(struct ice_rx_ring *rx_ring, int budget)
 		total_rx_pkts++;
 	}
 
-	first = rx_ring->first_desc;
-	while (cached_ntc != first) {
-		struct ice_rx_buf *buf = &rx_ring->rx_buf[cached_ntc];
-
-		if (buf->act & (ICE_XDP_TX | ICE_XDP_REDIR)) {
-			ice_rx_buf_adjust_pg_offset(buf, xdp->frame_sz);
-			xdp_xmit |= buf->act;
-		} else if (buf->act & ICE_XDP_CONSUMED) {
-			buf->pagecnt_bias++;
-		} else if (buf->act == ICE_XDP_PASS) {
-			ice_rx_buf_adjust_pg_offset(buf, xdp->frame_sz);
-		}
-
-		ice_put_rx_buf(rx_ring, buf);
-		if (++cached_ntc >= cnt)
-			cached_ntc = 0;
-	}
 	rx_ring->next_to_clean = ntc;
 	/* return up to cleaned_count buffers to hardware */
 	failure = ice_alloc_rx_bufs(rx_ring, ICE_RX_DESC_UNUSED(rx_ring));

drivers/net/ethernet/intel/ice/ice_txrx.h

@@ -201,7 +201,6 @@ struct ice_rx_buf {
 	struct page *page;
 	unsigned int page_offset;
 	unsigned int pgcnt;
-	unsigned int act;
 	unsigned int pagecnt_bias;
 };
 

drivers/net/ethernet/intel/ice/ice_txrx_lib.h

@@ -5,49 +5,6 @@
 #define _ICE_TXRX_LIB_H_
 #include "ice.h"
 
-/**
- * ice_set_rx_bufs_act - propagate Rx buffer action to frags
- * @xdp: XDP buffer representing frame (linear and frags part)
- * @rx_ring: Rx ring struct
- * act: action to store onto Rx buffers related to XDP buffer parts
- *
- * Set action that should be taken before putting Rx buffer from first frag
- * to the last.
- */
-static inline void
-ice_set_rx_bufs_act(struct xdp_buff *xdp, const struct ice_rx_ring *rx_ring,
-		    const unsigned int act)
-{
-	u32 sinfo_frags = xdp_get_shared_info_from_buff(xdp)->nr_frags;
-	u32 nr_frags = rx_ring->nr_frags + 1;
-	u32 idx = rx_ring->first_desc;
-	u32 cnt = rx_ring->count;
-	struct ice_rx_buf *buf;
-
-	for (int i = 0; i < nr_frags; i++) {
-		buf = &rx_ring->rx_buf[idx];
-		buf->act = act;
-
-		if (++idx == cnt)
-			idx = 0;
-	}
-
-	/* adjust pagecnt_bias on frags freed by XDP prog */
-	if (sinfo_frags < rx_ring->nr_frags && act == ICE_XDP_CONSUMED) {
-		u32 delta = rx_ring->nr_frags - sinfo_frags;
-
-		while (delta) {
-			if (idx == 0)
-				idx = cnt - 1;
-			else
-				idx--;
-			buf = &rx_ring->rx_buf[idx];
-			buf->pagecnt_bias--;
-			delta--;
-		}
-	}
-}
-
 /**
  * ice_test_staterr - tests bits in Rx descriptor status and error fields
  * @status_err_n: Rx descriptor status_error0 or status_error1 bits