[PATCH 25.11 0/3] remove fallbacks for old Linux versions

[PATCH 25.11 0/3] remove fallbacks for old Linux versions

[Bruce Richardson]

We no longer support versions of linux before 4.19[1], therefore
all supported linux versions support F_ADD_SEALS (Linux 3.17+) and
MFD_HUGETLB (Linux 4.14+), so no need to have #ifdefs and fallbacks to
support systems which do not support those features.

[1] https://doc.dpdk.org/guides/linux_gsg/sys_reqs.html#system-software

Bruce Richardson (3):
  eal/linux: remove fallbacks for old Linux versions
  vhost: : remove fallbacks for old Linux versions
  memif: : remove fallbacks for old Linux versions

 drivers/net/memif/rte_eth_memif.h |  41 -------
 lib/eal/linux/eal_memalloc.c      | 174 +++++-------------------------
 lib/eal/linux/eal_memory.c        |   7 --
 lib/vhost/vhost_user.c            |   7 --
 4 files changed, 24 insertions(+), 205 deletions(-)

-- 
2.48.1

[PATCH 25.11 1/3] eal/linux: remove fallbacks for old Linux versions

[Bruce Richardson]

All supported linux versions support F_ADD_SEALS (Linux 3.17+) and
MFD_HUGETLB (Linux 4.14+), so no need to have #ifdefs and fallbacks to
support systems which do not support those features.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 lib/eal/linux/eal_memalloc.c | 174 +++++------------------------------
 lib/eal/linux/eal_memory.c   |   7 --
 2 files changed, 24 insertions(+), 157 deletions(-)

diff --git a/lib/eal/linux/eal_memalloc.c b/lib/eal/linux/eal_memalloc.c
index e354efc95d..1e60e21620 100644
--- a/lib/eal/linux/eal_memalloc.c
+++ b/lib/eal/linux/eal_memalloc.c
@@ -16,10 +16,7 @@
 #include <fcntl.h>
 #include <signal.h>
 #include <setjmp.h>
-#ifdef F_ADD_SEALS /* if file sealing is supported, so is memfd */
 #include <linux/memfd.h>
-#define MEMFD_SUPPORTED
-#endif
 #ifdef RTE_EAL_NUMA_AWARE_HUGEPAGES
 #include <numa.h>
 #include <numaif.h>
@@ -47,24 +44,6 @@ const int anonymous_hugepages_supported =
 #define RTE_MAP_HUGE_SHIFT 26
 #endif
 
-/*
- * we've already checked memfd support at compile-time, but we also need to
- * check if we can create hugepage files with memfd.
- *
- * also, this is not a constant, because while we may be *compiled* with memfd
- * hugetlbfs support, we might not be *running* on a system that supports memfd
- * and/or memfd with hugetlbfs, so we need to be able to adjust this flag at
- * runtime, and fall back to anonymous memory.
- */
-static int memfd_create_supported =
-#ifdef MFD_HUGETLB
-		1;
-#define RTE_MFD_HUGETLB MFD_HUGETLB
-#else
-		0;
-#define RTE_MFD_HUGETLB 4U
-#endif
-
 /*
  * not all kernel version support fallocate on hugetlbfs, so fall back to
  * ftruncate and disallow deallocation if fallocate is not supported.
@@ -236,11 +215,10 @@ get_seg_memfd(struct hugepage_info *hi __rte_unused,
 		unsigned int list_idx __rte_unused,
 		unsigned int seg_idx __rte_unused)
 {
-#ifdef MEMFD_SUPPORTED
 	int fd;
 	char segname[250]; /* as per manpage, limit is 249 bytes plus null */
 
-	int flags = RTE_MFD_HUGETLB | pagesz_flags(hi->hugepage_sz);
+	int flags = MFD_HUGETLB | pagesz_flags(hi->hugepage_sz);
 	const struct internal_config *internal_conf =
 		eal_get_internal_configuration();
 
@@ -273,8 +251,6 @@ get_seg_memfd(struct hugepage_info *hi __rte_unused,
 		}
 	}
 	return fd;
-#endif
-	return -1;
 }
 
 static int
@@ -539,66 +515,40 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
 		EAL_LOG(ERR, "Anonymous hugepages not supported, in-memory mode cannot allocate memory");
 		return -1;
 	}
-	if (internal_conf->in_memory && !memfd_create_supported &&
-			internal_conf->single_file_segments) {
-		EAL_LOG(ERR, "Single-file segments are not supported without memfd support");
-		return -1;
-	}
 
-	/* in-memory without memfd is a special case */
+	/* use memfd for in-memory mode */
 	int mmap_flags;
 
-	if (internal_conf->in_memory && !memfd_create_supported) {
-		const int in_memory_flags = MAP_HUGETLB | MAP_FIXED |
-				MAP_PRIVATE | MAP_ANONYMOUS;
-		int pagesz_flag;
+	/* takes out a read lock on segment or segment list */
+	fd = get_seg_fd(path, sizeof(path), hi, list_idx, seg_idx, &dirty);
+	if (fd < 0) {
+		EAL_LOG(ERR, "Couldn't get fd on hugepage file");
+		return -1;
+	}
 
-		pagesz_flag = pagesz_flags(alloc_sz);
-		fd = -1;
-		dirty = false;
-		mmap_flags = in_memory_flags | pagesz_flag;
+	if (internal_conf->single_file_segments) {
+		map_offset = seg_idx * alloc_sz;
+		ret = resize_hugefile(fd, map_offset, alloc_sz, true, &dirty);
+		if (ret < 0)
+			goto resized;
 
-		/* single-file segments codepath will never be active
-		 * here because in-memory mode is incompatible with the
-		 * fallback path, and it's stopped at EAL initialization
-		 * stage.
-		 */
-		map_offset = 0;
+		fd_list[list_idx].count++;
 	} else {
-		/* takes out a read lock on segment or segment list */
-		fd = get_seg_fd(path, sizeof(path), hi, list_idx, seg_idx,
-				&dirty);
-		if (fd < 0) {
-			EAL_LOG(ERR, "Couldn't get fd on hugepage file");
-			return -1;
+		map_offset = 0;
+		if (ftruncate(fd, alloc_sz) < 0) {
+			EAL_LOG(DEBUG, "%s(): ftruncate() failed: %s", __func__, strerror(errno));
+			goto resized;
 		}
-
-		if (internal_conf->single_file_segments) {
-			map_offset = seg_idx * alloc_sz;
-			ret = resize_hugefile(fd, map_offset, alloc_sz, true,
-					&dirty);
-			if (ret < 0)
-				goto resized;
-
-			fd_list[list_idx].count++;
-		} else {
-			map_offset = 0;
-			if (ftruncate(fd, alloc_sz) < 0) {
-				EAL_LOG(DEBUG, "%s(): ftruncate() failed: %s",
+		if (internal_conf->hugepage_file.unlink_before_mapping &&
+				!internal_conf->in_memory) {
+			if (unlink(path)) {
+				EAL_LOG(DEBUG, "%s(): unlink() failed: %s",
 					__func__, strerror(errno));
 				goto resized;
 			}
-			if (internal_conf->hugepage_file.unlink_before_mapping &&
-					!internal_conf->in_memory) {
-				if (unlink(path)) {
-					EAL_LOG(DEBUG, "%s(): unlink() failed: %s",
-						__func__, strerror(errno));
-					goto resized;
-				}
-			}
 		}
-		mmap_flags = MAP_SHARED | MAP_POPULATE | MAP_FIXED;
 	}
+	mmap_flags = MAP_SHARED | MAP_POPULATE | MAP_FIXED;
 
 	huge_register_sigbus();
 
@@ -754,12 +704,6 @@ free_seg(struct rte_memseg *ms, struct hugepage_info *hi,
 
 	eal_mem_set_dump(ms->addr, ms->len, false);
 
-	/* if we're using anonymous hugepages, nothing to be done */
-	if (internal_conf->in_memory && !memfd_create_supported) {
-		memset(ms, 0, sizeof(*ms));
-		return 0;
-	}
-
 	/* if we are not in single file segments mode, we're going to unmap the
 	 * segment and thus drop the lock on original fd, but hugepage dir is
 	 * now locked so we can take out another one without races.
@@ -1624,16 +1568,6 @@ eal_memalloc_get_seg_fd(int list_idx, int seg_idx)
 	const struct internal_config *internal_conf =
 		eal_get_internal_configuration();
 
-	if (internal_conf->in_memory || internal_conf->no_hugetlbfs) {
-#ifndef MEMFD_SUPPORTED
-		/* in in-memory or no-huge mode, we rely on memfd support */
-		return -ENOTSUP;
-#endif
-		/* memfd supported, but hugetlbfs memfd may not be */
-		if (!internal_conf->no_hugetlbfs && !memfd_create_supported)
-			return -ENOTSUP;
-	}
-
 	if (internal_conf->single_file_segments) {
 		fd = fd_list[list_idx].memseg_list_fd;
 	} else if (fd_list[list_idx].len == 0) {
@@ -1647,37 +1581,6 @@ eal_memalloc_get_seg_fd(int list_idx, int seg_idx)
 	return fd;
 }
 
-static int
-test_memfd_create(void)
-{
-#ifdef MEMFD_SUPPORTED
-	const struct internal_config *internal_conf =
-		eal_get_internal_configuration();
-	unsigned int i;
-	for (i = 0; i < internal_conf->num_hugepage_sizes; i++) {
-		uint64_t pagesz = internal_conf->hugepage_info[i].hugepage_sz;
-		int pagesz_flag = pagesz_flags(pagesz);
-		int flags;
-
-		flags = pagesz_flag | RTE_MFD_HUGETLB;
-		int fd = memfd_create("test", flags);
-		if (fd < 0) {
-			/* we failed - let memalloc know this isn't working */
-			if (errno == EINVAL) {
-				memfd_create_supported = 0;
-				return 0; /* not supported */
-			}
-
-			/* we got other error - something's wrong */
-			return -1; /* error */
-		}
-		close(fd);
-		return 1; /* supported */
-	}
-#endif
-	return 0; /* not supported */
-}
-
 int
 eal_memalloc_get_seg_fd_offset(int list_idx, int seg_idx, size_t *offset)
 {
@@ -1685,16 +1588,6 @@ eal_memalloc_get_seg_fd_offset(int list_idx, int seg_idx, size_t *offset)
 	const struct internal_config *internal_conf =
 		eal_get_internal_configuration();
 
-	if (internal_conf->in_memory || internal_conf->no_hugetlbfs) {
-#ifndef MEMFD_SUPPORTED
-		/* in in-memory or no-huge mode, we rely on memfd support */
-		return -ENOTSUP;
-#endif
-		/* memfd supported, but hugetlbfs memfd may not be */
-		if (!internal_conf->no_hugetlbfs && !memfd_create_supported)
-			return -ENOTSUP;
-	}
-
 	if (internal_conf->single_file_segments) {
 		size_t pgsz = mcfg->memsegs[list_idx].page_sz;
 
@@ -1747,26 +1640,7 @@ eal_memalloc_init(void)
 			return -1;
 	if (rte_eal_process_type() == RTE_PROC_PRIMARY &&
 			internal_conf->in_memory) {
-		int mfd_res = test_memfd_create();
-
-		if (mfd_res < 0) {
-			EAL_LOG(ERR, "Unable to check if memfd is supported");
-			return -1;
-		}
-		if (mfd_res == 1)
-			EAL_LOG(DEBUG, "Using memfd for anonymous memory");
-		else
-			EAL_LOG(INFO, "Using memfd is not supported, falling back to anonymous hugepages");
-
-		/* we only support single-file segments mode with in-memory mode
-		 * if we support hugetlbfs with memfd_create. this code will
-		 * test if we do.
-		 */
-		if (internal_conf->single_file_segments &&
-				mfd_res != 1) {
-			EAL_LOG(ERR, "Single-file segments mode cannot be used without memfd support");
-			return -1;
-		}
+		EAL_LOG(DEBUG, "Using memfd for anonymous memory");
 		/* this cannot ever happen but better safe than sorry */
 		if (!anonymous_hugepages_supported) {
 			EAL_LOG(ERR, "Using anonymous memory is not supported");
diff --git a/lib/eal/linux/eal_memory.c b/lib/eal/linux/eal_memory.c
index e433c1afee..ee964446c7 100644
--- a/lib/eal/linux/eal_memory.c
+++ b/lib/eal/linux/eal_memory.c
@@ -20,9 +20,6 @@
 #include <limits.h>
 #include <signal.h>
 #include <setjmp.h>
-#ifdef F_ADD_SEALS /* if file sealing is supported, so is memfd */
-#define MEMFD_SUPPORTED
-#endif
 #ifdef RTE_EAL_NUMA_AWARE_HUGEPAGES
 #include <numa.h>
 #include <numaif.h>
@@ -1161,9 +1158,7 @@ eal_legacy_hugepage_init(void)
 		size_t mem_sz;
 		struct rte_memseg_list *msl;
 		int n_segs, fd, flags;
-#ifdef MEMFD_SUPPORTED
 		int memfd;
-#endif
 		uint64_t page_sz;
 
 		/* nohuge mode is legacy mode */
@@ -1188,7 +1183,6 @@ eal_legacy_hugepage_init(void)
 		fd = -1;
 		flags = MAP_PRIVATE | MAP_ANONYMOUS;
 
-#ifdef MEMFD_SUPPORTED
 		/* create a memfd and store it in the segment fd table */
 		memfd = memfd_create("nohuge", 0);
 		if (memfd < 0) {
@@ -1213,7 +1207,6 @@ eal_legacy_hugepage_init(void)
 				flags = MAP_SHARED;
 			}
 		}
-#endif
 		/* preallocate address space for the memory, so that it can be
 		 * fit into the DMA mask.
 		 */
-- 
2.48.1

[PATCH 25.11 2/3] vhost: : remove fallbacks for old Linux versions

[Bruce Richardson]

All supported linux versions support F_ADD_SEALS (Linux 3.17+) and
MFD_HUGETLB (Linux 4.14+), so no need to have #ifdefs and fallbacks to
support systems which do not support those features.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 lib/vhost/vhost_user.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index b73dec6a22..4bfb13fb98 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -36,10 +36,7 @@
 #ifdef RTE_LIBRTE_VHOST_POSTCOPY
 #include <linux/userfaultfd.h>
 #endif
-#ifdef F_ADD_SEALS /* if file sealing is supported, so is memfd */
 #include <linux/memfd.h>
-#define MEMFD_SUPPORTED
-#endif
 
 #include <eal_export.h>
 #include <rte_common.h>
@@ -1627,11 +1624,7 @@ inflight_mem_alloc(struct virtio_net *dev, const char *name, size_t size, int *f
 	char fname[20] = "/tmp/memfd-XXXXXX";
 
 	*fd = -1;
-#ifdef MEMFD_SUPPORTED
 	mfd = memfd_create(name, MFD_CLOEXEC);
-#else
-	RTE_SET_USED(name);
-#endif
 	if (mfd == -1) {
 		mfd = mkstemp(fname);
 		if (mfd == -1) {
-- 
2.48.1

[PATCH 25.11 3/3] memif: : remove fallbacks for old Linux versions

[Bruce Richardson]

All supported linux versions support F_ADD_SEALS (Linux 3.17+) and
MFD_HUGETLB (Linux 4.14+), so no need to have #ifdefs and fallbacks to
support systems which do not support those features.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 drivers/net/memif/rte_eth_memif.h | 41 -------------------------------
 1 file changed, 41 deletions(-)

diff --git a/drivers/net/memif/rte_eth_memif.h b/drivers/net/memif/rte_eth_memif.h
index 8e45a3ab78..d4e625ab51 100644
--- a/drivers/net/memif/rte_eth_memif.h
+++ b/drivers/net/memif/rte_eth_memif.h
@@ -169,37 +169,6 @@ int memif_init_regions_and_queues(struct rte_eth_dev *dev);
  */
 const char *memif_version(void);
 
-#ifndef MFD_HUGETLB
-#ifndef __NR_memfd_create
-
-#if defined __x86_64__
-#define __NR_memfd_create 319
-#elif defined __x86_32__
-#define __NR_memfd_create 1073742143
-#elif defined __arm__
-#define __NR_memfd_create 385
-#elif defined __aarch64__
-#define __NR_memfd_create 279
-#elif defined __powerpc__
-#define __NR_memfd_create 360
-#elif defined __i386__
-#define __NR_memfd_create 356
-#elif defined __riscv
-#define __NR_memfd_create 279
-#elif defined __loongarch__
-#define __NR_memfd_create 279
-#else
-#error "__NR_memfd_create unknown for this architecture"
-#endif
-
-#endif				/* __NR_memfd_create */
-
-static inline int memfd_create(const char *name, unsigned int flags)
-{
-	return syscall(__NR_memfd_create, name, flags);
-}
-#endif				/* MFD_HUGETLB */
-
 #ifndef F_LINUX_SPECIFIC_BASE
 #define F_LINUX_SPECIFIC_BASE 1024
 #endif
@@ -208,14 +177,4 @@ static inline int memfd_create(const char *name, unsigned int flags)
 #define MFD_ALLOW_SEALING       0x0002U
 #endif
 
-#ifndef F_ADD_SEALS
-#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9)
-#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10)
-
-#define F_SEAL_SEAL     0x0001	/* prevent further seals from being set */
-#define F_SEAL_SHRINK   0x0002	/* prevent file from shrinking */
-#define F_SEAL_GROW     0x0004	/* prevent file from growing */
-#define F_SEAL_WRITE    0x0008	/* prevent writes */
-#endif
-
 #endif				/* RTE_ETH_MEMIF_H */
-- 
2.48.1

Re: [PATCH 25.11 0/3] remove fallbacks for old Linux versions

[Stephen Hemminger]

On Mon, 30 Jun 2025 13:29:01 +0000
Bruce Richardson <bruce.richardson@intel.com> wrote:

> We no longer support versions of linux before 4.19[1], therefore
> all supported linux versions support F_ADD_SEALS (Linux 3.17+) and
> MFD_HUGETLB (Linux 4.14+), so no need to have #ifdefs and fallbacks to
> support systems which do not support those features.
> 
> [1] https://doc.dpdk.org/guides/linux_gsg/sys_reqs.html#system-software
> 
> Bruce Richardson (3):
>   eal/linux: remove fallbacks for old Linux versions
>   vhost: : remove fallbacks for old Linux versions
>   memif: : remove fallbacks for old Linux versions
> 
>  drivers/net/memif/rte_eth_memif.h |  41 -------
>  lib/eal/linux/eal_memalloc.c      | 174 +++++-------------------------
>  lib/eal/linux/eal_memory.c        |   7 --
>  lib/vhost/vhost_user.c            |   7 --
>  4 files changed, 24 insertions(+), 205 deletions(-)
> 

Series-Acked-by: Stephen Hemminger <stephen@networkplumber.org>