Date: Thu, 7 Aug 2025 18:46:53 GMT From: =?utf-8?Q?Jean-S=C3=A9bastien?= =?utf-8?Q?P=C3=A9dron?= <dumbbell@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: c0fc0facf877 - main - linuxkpi: Call `lkpi_fpu_safe_exec()` in the implementation of kvmalloc() Message-ID: <202508071846.577IkrAY018706@gitrepo.freebsd.org>
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The branch main has been updated by dumbbell: URL: https://cgit.FreeBSD.org/src/commit/?id=c0fc0facf877d4e2ad5843d59c15d0d464432962 commit c0fc0facf877d4e2ad5843d59c15d0d464432962 Author: Jean-Sébastien Pédron <dumbbell@FreeBSD.org> AuthorDate: 2025-07-26 12:17:26 +0000 Commit: Jean-Sébastien Pédron <dumbbell@FreeBSD.org> CommitDate: 2025-08-07 18:46:15 +0000 linuxkpi: Call `lkpi_fpu_safe_exec()` in the implementation of kvmalloc() `kvmalloc()` was a simple wrapper around the FreeBSD native `malloc()`. Unlike the more involved implementation of `kmalloc()`, it didn't end and being the FPU context around the actual call to `malloc()`. This caused the following panic in the amdgup DRM driver: panic: malloc: called with spinlock or critical section held ... triggered by the call: struct dc_3dlut *lut = kvzalloc(sizeof(*lut), GFP_KERNEL); (for the record, GFP_KERNEL is defined as M_WAITOK) Replicating the same behaviour as `kmalloc()`, in other words, ending the FPU context before the call to the underlying `malloc()`, and beginning it again afterwards solves the problem. Reviewed by: olce Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D51557 --- sys/compat/linuxkpi/common/include/linux/slab.h | 3 ++- sys/compat/linuxkpi/common/src/linux_slab.c | 17 +++++++++++++++++ 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/sys/compat/linuxkpi/common/include/linux/slab.h b/sys/compat/linuxkpi/common/include/linux/slab.h index efa5c8cb67b3..47e3d133eb6c 100644 --- a/sys/compat/linuxkpi/common/include/linux/slab.h +++ b/sys/compat/linuxkpi/common/include/linux/slab.h @@ -99,6 +99,7 @@ void lkpi_kmem_cache_free(struct linux_kmem_cache *, void *); void linux_kmem_cache_destroy(struct linux_kmem_cache *); void *lkpi_kmalloc(size_t, gfp_t); +void *lkpi_kvmalloc(size_t, gfp_t); void *lkpi___kmalloc(size_t, gfp_t); void *lkpi___kmalloc_node(size_t, gfp_t, int); void *lkpi_krealloc(void *, size_t, gfp_t); @@ -225,7 +226,7 @@ vmalloc_32(size_t size) static inline void * kvmalloc(size_t size, gfp_t flags) { - return (malloc(size, M_KMALLOC, linux_check_m_flags(flags))); + return (lkpi_kvmalloc(size, flags)); } static inline void * diff --git a/sys/compat/linuxkpi/common/src/linux_slab.c b/sys/compat/linuxkpi/common/src/linux_slab.c index 3d75ca480661..6f71d17a3770 100644 --- a/sys/compat/linuxkpi/common/src/linux_slab.c +++ b/sys/compat/linuxkpi/common/src/linux_slab.c @@ -296,6 +296,23 @@ lkpi_kmalloc(size_t size, gfp_t flags) return(lmc.addr); } +static void +lkpi_kvmalloc_cb(void *ctx) +{ + struct lkpi_kmalloc_ctx *lmc = ctx; + + lmc->addr = malloc(lmc->size, M_KMALLOC, linux_check_m_flags(lmc->flags)); +} + +void * +lkpi_kvmalloc(size_t size, gfp_t flags) +{ + struct lkpi_kmalloc_ctx lmc = { .size = size, .flags = flags }; + + lkpi_fpu_safe_exec(&lkpi_kvmalloc_cb, &lmc); + return(lmc.addr); +} + static void linux_kfree_async_fn(void *context, int pending) {
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