git: 19df0c5abcb9 - main - LinuxKPI: make __kmalloc() play by the rules

From: Bjoern A. Zeeb <bz_at_FreeBSD.org>
Date: Fri, 14 Mar 2025 16:25:40 UTC
The branch main has been updated by bz:

URL: https://cgit.FreeBSD.org/src/commit/?id=19df0c5abcb9d4e951e610b6de98d4d8a00bd5f9

commit 19df0c5abcb9d4e951e610b6de98d4d8a00bd5f9
Author:     Bjoern A. Zeeb <bz@FreeBSD.org>
AuthorDate: 2024-09-12 18:11:01 +0000
Commit:     Bjoern A. Zeeb <bz@FreeBSD.org>
CommitDate: 2025-03-14 16:24:52 +0000

    LinuxKPI: make __kmalloc() play by the rules
    
    According to Documentation/core-api/dma-api.rst kmalloc() is supposd
    to provide physically contiguous memory. [1]
    
    In order to guarantee that allocations are contiguous even if using
    PAGE_SIZE or larger check the size and use contigmalloc if needed.
    This makes use of 9e6544dd6e02 (and following) allowing free(9) to
    also work for contigmalloced memory.
    
    Sponsored by:   The FreeBSD Foundation
    Pointed out by: jhb [1]
    Reviewed by:    jhb, emaste
    MFC after:      3 days
    Differential Revision: https://reviews.freebsd.org/D46656
---
 sys/compat/linuxkpi/common/src/linux_slab.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/sys/compat/linuxkpi/common/src/linux_slab.c b/sys/compat/linuxkpi/common/src/linux_slab.c
index 72b35fee9214..5be4c1ec674c 100644
--- a/sys/compat/linuxkpi/common/src/linux_slab.c
+++ b/sys/compat/linuxkpi/common/src/linux_slab.c
@@ -215,7 +215,11 @@ lkpi___kmalloc(size_t size, gfp_t flags)
 	/* sizeof(struct llist_node) is used for kfree_async(). */
 	_s = MAX(size, sizeof(struct llist_node));
 
-	return (malloc(_s, M_KMALLOC, linux_check_m_flags(flags)));
+	if (_s < PAGE_SIZE)
+		return (malloc(_s, M_KMALLOC, linux_check_m_flags(flags)));
+	else
+		return (contigmalloc(_s, M_KMALLOC, linux_check_m_flags(flags),
+		    0, -1UL, PAGE_SIZE, 0));
 }
 
 struct lkpi_kmalloc_ctx {