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libhsakmt: Don't use MADV_DONTFORK for paged memory #330

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libhsakmt: Don't use MADV_DONTFORK for paged memory #330

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d466ce6
libhsakmt: Don't use MADV_DONTFORK for paged memory
hkasivis Jul 23, 2025
e9afc96
Merge branch 'amd-staging' into hkasivis/fix-madvise-nofork
hkasivis Jul 25, 2025
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14 changes: 7 additions & 7 deletions libhsakmt/src/fmm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1843,7 +1843,6 @@ static void *fmm_allocate_host_gpu(uint32_t gpu_id, uint32_t node_id, void *addr
{
manageable_aperture_t *aperture;
vm_object_t *vm_obj = NULL;
int flags = MADV_DONTFORK;
uint64_t mmap_offset;
int32_t gpu_drm_fd;
uint32_t ioc_flags;
Expand All @@ -1852,11 +1851,6 @@ static void *fmm_allocate_host_gpu(uint32_t gpu_id, uint32_t node_id, void *addr
uint64_t size;
void *mem;

/* set madvise flags to HUGEPAGE always for 2MB pages */
if (MemorySizeInBytes >= (2 * 1024 * 1024))
flags |= MADV_HUGEPAGE;


if (!g_first_gpu_mem)
return NULL;

Expand Down Expand Up @@ -1895,6 +1889,12 @@ static void *fmm_allocate_host_gpu(uint32_t gpu_id, uint32_t node_id, void *addr
* memory is allocated from KFD
*/
if (!mflags.ui32.NonPaged && svm.userptr_for_paged_mem) {
int advice = MADV_NORMAL;

/* set madvise flags to HUGEPAGE always for 2MB pages */
if (MemorySizeInBytes >= (2 * 1024 * 1024))
advice = MADV_HUGEPAGE;

/* Allocate address space */
pthread_mutex_lock(&aperture->fmm_mutex);
mem = aperture_allocate_area_aligned(aperture, address, size, alignment);
Expand All @@ -1916,7 +1916,7 @@ static void *fmm_allocate_host_gpu(uint32_t gpu_id, uint32_t node_id, void *addr
* fork. This avoids MMU notifiers and evictions due to user
* memory mappings on fork.
*/
madvise(mem, MemorySizeInBytes, flags);
madvise(mem, MemorySizeInBytes, advice);

/* Create userptr BO */
mmap_offset = (uint64_t)mem;
Expand Down
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