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drm/xe/uapi: Introduce a flag to disallow vm overcommit in fault mode

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Some compute applications may try to allocate device memory to probe
how much device memory is actually available, assuming that the
application will be the only one running on the particular GPU.

That strategy fails in fault mode since it allows VM overcommit.

While this could be resolved in user-space it's further complicated
by cgroups potentially restricting the amount of memory available
to the application.

Introduce a vm create flag, DRM_XE_VM_CREATE_NO_VM_OVERCOMMIT, that
allows fault mode to mimic the behaviour of !fault mode WRT this. It
blocks evicting same vm bos during VM_BIND processing. However,
it does *not* block evicting same-vm bos during pagefault
processing, preferring eviction rather than VM banning in
OOM situations.

Cc: John Falkowski <john.falkowski@intel.com>
Cc: Michal Mrozek <michal.mrozek@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20260204153320.17989-1-thomas.hellstrom@linux.intel.com
This commit is contained in:
Thomas Hellström
2026-02-04 16:33:20 +01:00
parent 1aafc0a991
commit 369cc88049
4 changed files with 23 additions and 2 deletions
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6
include/uapi/drm/xe_drm.h
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@@ -969,6 +969,11 @@ struct drm_xe_gem_mmap_offset {
* demand when accessed, and also allows per-VM overcommit of memory.
* The xe driver internally uses recoverable pagefaults to implement
* this.
* - %DRM_XE_VM_CREATE_FLAG_NO_VM_OVERCOMMIT - Requires also
* DRM_XE_VM_CREATE_FLAG_FAULT_MODE. This disallows per-VM overcommit
* but only during a &DRM_IOCTL_XE_VM_BIND operation with the
* %DRM_XE_VM_BIND_FLAG_IMMEDIATE flag set. This may be useful for
* user-space naively probing the amount of available memory.
*/
struct drm_xe_vm_create {
/** @extensions: Pointer to the first extension struct, if any */
@@ -977,6 +982,7 @@ struct drm_xe_vm_create {
#define DRM_XE_VM_CREATE_FLAG_SCRATCH_PAGE (1 << 0)
#define DRM_XE_VM_CREATE_FLAG_LR_MODE (1 << 1)
#define DRM_XE_VM_CREATE_FLAG_FAULT_MODE (1 << 2)
#define DRM_XE_VM_CREATE_FLAG_NO_VM_OVERCOMMIT (1 << 3)
/** @flags: Flags */
__u32 flags;