patch 'eal/linux: fix legacy mem init with many segments' has been queued to stable release 20.11.9

[luca.boccassi@gmail.com]

Hi,

FYI, your patch has been queued to stable release 20.11.9

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 06/17/23. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/bluca/dpdk-stable

This queued commit can be viewed at:
https://github.com/bluca/dpdk-stable/commit/154506b8fae5c3b413bd7974ec6648c15f120a07

Thanks.

Luca Boccassi

---
From 154506b8fae5c3b413bd7974ec6648c15f120a07 Mon Sep 17 00:00:00 2001
From: Fengnan Chang <changfengnan@bytedance.com>
Date: Mon, 29 May 2023 19:21:30 +0800
Subject: [PATCH] eal/linux: fix legacy mem init with many segments

[ upstream commit 51a5a72e2a82986b02244fcdd89c6571bc503de3 ]

Under legacy mode, if the number of continuous memsegs greater
than RTE_MAX_MEMSEG_PER_LIST, eal init will failed even though
another memseg list is empty, because only one memseg list used
to check in remap_needed_hugepages.
Fix this by make remap_segment return how many segments mapped,
remap_segment try to map most contiguous segments it can, if it
exceed its capacity, remap_needed_hugepages will continue to
map other left pages.

For example:
hugepage configure:
cat /sys/devices/system/node/node*/hugepages/hugepages-2048kB/nr_hugepages
10241
10239

startup log:
EAL: Detected memory type: socket_id:0 hugepage_sz:2097152
EAL: Detected memory type: socket_id:1 hugepage_sz:2097152
EAL: Creating 4 segment lists: n_segs:8192 socket_id:0 hugepage_sz:2097152
EAL: Creating 4 segment lists: n_segs:8192 socket_id:1 hugepage_sz:2097152
EAL: Requesting 13370 pages of size 2MB from socket 0
EAL: Requesting 7110 pages of size 2MB from socket 1
EAL: Attempting to map 14220M on socket 1
EAL: Allocated 14220M on socket 1
EAL: Attempting to map 26740M on socket 0
EAL: Could not find space for memseg. Please increase 32768 and/or 65536 in
configuration.
EAL: Couldn't remap hugepage files into memseg lists
EAL: FATAL: Cannot init memory
EAL: Cannot init memory

Fixes: 66cc45e293ed ("mem: replace memseg with memseg lists")

Signed-off-by: Fengnan Chang <changfengnan@bytedance.com>
Signed-off-by: Lin Li <lilintjpu@bytedance.com>
Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 lib/librte_eal/linux/eal_memory.c | 51 ++++++++++++++++++++++---------
 1 file changed, 36 insertions(+), 15 deletions(-)

diff --git a/lib/librte_eal/linux/eal_memory.c b/lib/librte_eal/linux/eal_memory.c
index fda6a159d5..3bd0bc17c5 100644
--- a/lib/librte_eal/linux/eal_memory.c
+++ b/lib/librte_eal/linux/eal_memory.c
@@ -686,6 +686,7 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
 
 	/* find free space in memseg lists */
 	for (msl_idx = 0; msl_idx < RTE_MAX_MEMSEG_LISTS; msl_idx++) {
+		int free_len;
 		bool empty;
 		msl = &mcfg->memsegs[msl_idx];
 		arr = &msl->memseg_arr;
@@ -697,18 +698,26 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
 
 		/* leave space for a hole if array is not empty */
 		empty = arr->count == 0;
-		ms_idx = rte_fbarray_find_next_n_free(arr, 0,
-				seg_len + (empty ? 0 : 1));
-
-		/* memseg list is full? */
+		/* find start of the biggest contiguous block and its size */
+		ms_idx = rte_fbarray_find_biggest_free(arr, 0);
 		if (ms_idx < 0)
 			continue;
-
+		/* hole is 1 segment long, so at least two segments long. */
+		free_len = rte_fbarray_find_contig_free(arr, ms_idx);
+		if (free_len < 2)
+			continue;
 		/* leave some space between memsegs, they are not IOVA
 		 * contiguous, so they shouldn't be VA contiguous either.
 		 */
-		if (!empty)
+		if (!empty) {
 			ms_idx++;
+			free_len--;
+		}
+
+		/* we might not get all of the space we wanted */
+		free_len = RTE_MIN(seg_len, free_len);
+		seg_end = seg_start + free_len;
+		seg_len = seg_end - seg_start;
 		break;
 	}
 	if (msl_idx == RTE_MAX_MEMSEG_LISTS) {
@@ -792,7 +801,7 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
 	}
 	RTE_LOG(DEBUG, EAL, "Allocated %" PRIu64 "M on socket %i\n",
 			(seg_len * page_sz) >> 20, socket_id);
-	return 0;
+	return seg_len;
 }
 
 static uint64_t
@@ -1027,10 +1036,16 @@ remap_needed_hugepages(struct hugepage_file *hugepages, int n_pages)
 		if (new_memseg) {
 			/* if this isn't the first time, remap segment */
 			if (cur_page != 0) {
-				ret = remap_segment(hugepages, seg_start_page,
-						cur_page);
-				if (ret != 0)
-					return -1;
+				int n_remapped = 0;
+				int n_needed = cur_page - seg_start_page;
+				while (n_remapped < n_needed) {
+					ret = remap_segment(hugepages, seg_start_page,
+							cur_page);
+					if (ret < 0)
+						return -1;
+					n_remapped += ret;
+					seg_start_page += ret;
+				}
 			}
 			/* remember where we started */
 			seg_start_page = cur_page;
@@ -1039,10 +1054,16 @@ remap_needed_hugepages(struct hugepage_file *hugepages, int n_pages)
 	}
 	/* we were stopped, but we didn't remap the last segment, do it now */
 	if (cur_page != 0) {
-		ret = remap_segment(hugepages, seg_start_page,
-				cur_page);
-		if (ret != 0)
-			return -1;
+		int n_remapped = 0;
+		int n_needed = cur_page - seg_start_page;
+		while (n_remapped < n_needed) {
+			ret = remap_segment(hugepages, seg_start_page,
+					cur_page);
+			if (ret < 0)
+				return -1;
+			n_remapped += ret;
+			seg_start_page += ret;
+		}
 	}
 	return 0;
 }
-- 
2.39.2

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2023-06-15 01:56:35.763327389 +0100
+++ 0019-eal-linux-fix-legacy-mem-init-with-many-segments.patch	2023-06-15 01:56:34.539540691 +0100
@@ -1 +1 @@
-From 51a5a72e2a82986b02244fcdd89c6571bc503de3 Mon Sep 17 00:00:00 2001
+From 154506b8fae5c3b413bd7974ec6648c15f120a07 Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 51a5a72e2a82986b02244fcdd89c6571bc503de3 ]
+
@@ -38 +39,0 @@
-Cc: stable@dpdk.org
@@ -44,22 +45,8 @@
- .mailmap                   |  2 +-
- lib/eal/linux/eal_memory.c | 51 +++++++++++++++++++++++++++-----------
- 2 files changed, 37 insertions(+), 16 deletions(-)
-
-diff --git a/.mailmap b/.mailmap
-index 13167dc28b..853a89e9a4 100644
---- a/.mailmap
-+++ b/.mailmap
-@@ -766,7 +766,7 @@ Liming Sun <lsun@ezchip.com> <lsun@mellanox.com>
- Linfan Hu <zhongdahulinfan@163.com>
- Lingli Chen <linglix.chen@intel.com>
- Lingyu Liu <lingyu.liu@intel.com>
--Lin Li <lilin24@baidu.com>
-+Lin Li <lilintjpu@bytedance.com> <lilin24@baidu.com>
- Linsi Yuan <yuanlinsi01@baidu.com>
- Lior Margalit <lmargalit@nvidia.com>
- Li Qiang <liq3ea@163.com>
-diff --git a/lib/eal/linux/eal_memory.c b/lib/eal/linux/eal_memory.c
-index 60fc8cc6ca..0876974631 100644
---- a/lib/eal/linux/eal_memory.c
-+++ b/lib/eal/linux/eal_memory.c
-@@ -681,6 +681,7 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
+ lib/librte_eal/linux/eal_memory.c | 51 ++++++++++++++++++++++---------
+ 1 file changed, 36 insertions(+), 15 deletions(-)
+
+diff --git a/lib/librte_eal/linux/eal_memory.c b/lib/librte_eal/linux/eal_memory.c
+index fda6a159d5..3bd0bc17c5 100644
+--- a/lib/librte_eal/linux/eal_memory.c
++++ b/lib/librte_eal/linux/eal_memory.c
+@@ -686,6 +686,7 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
@@ -73 +60 @@
-@@ -692,18 +693,26 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
+@@ -697,18 +698,26 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
@@ -106 +93 @@
-@@ -787,7 +796,7 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
+@@ -792,7 +801,7 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
@@ -115 +102 @@
-@@ -1022,10 +1031,16 @@ remap_needed_hugepages(struct hugepage_file *hugepages, int n_pages)
+@@ -1027,10 +1036,16 @@ remap_needed_hugepages(struct hugepage_file *hugepages, int n_pages)
@@ -136 +123 @@
-@@ -1034,10 +1049,16 @@ remap_needed_hugepages(struct hugepage_file *hugepages, int n_pages)
+@@ -1039,10 +1054,16 @@ remap_needed_hugepages(struct hugepage_file *hugepages, int n_pages)