Commit a13edf9b92fc for kernel

commit a13edf9b92fc4700b3020d7ea547a3d64dd33b63
Author: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Date:   Thu Apr 9 08:31:11 2026 +0300

    drm/i915/gem: Drop check for changed VM in EXECBUF

    Since the introduction of d4433c7600f7 ("drm/i915/gem: Use the proto-context
    to handle create parameters (v5)") it has not been possible for VM to change
    after context creation so the check will never fail.

    Sima's analysis:

      This check was added in f7ce8639f6ff ("drm/i915/gem: Split the context's
      obj:vma lut into its own mutex") but without any hint in the commit
      message as to why. In another hunk of that commit there's a hint though in
      __eb_add_lut:

              /* user racing with ctx set-vm */

      This would mean that this bug was introduced in e0695db7298e ("drm/i915:
      Create/destroy VM (ppGTT) for use with contexts"), which allowed to change
      the gem_ctx->vm at runtime, opening up the race that was partially fixed
      in the earlier referenced commit about a year later.

      But it cannot be exploited anymore in anything remotely recent because
      with the introduction of proto-contexts we've made gem_ctx->vm invariant
      again, exactly to preemptively close all these potential issues.
      Specifically d4433c7600f7 ("drm/i915/gem: Use the proto-context to handle
      create parameters (v5)") is the vm specific part of the proto-context
      work.

    v3:
    - Include Sima's analysis and WARN_ON_ONCE

    v4:
    - Focus only on latest mainline codebase

    References: https://lore.kernel.org/all/20260324151741.29338-1-sosohero200@gmail.com/
    Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
    Cc: Linus Torvalds <torvalds@linuxfoundation.org>
    Cc: Simona Vetter <simona.vetter@ffwll.ch>
    Cc: Tvrtko Ursulin <tursulin@ursulin.net>
    Cc: Andi Shyti <andi.shyti@kernel.org>
    Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
    Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
    Link: https://patch.msgid.link/20260409053111.8914-1-joonas.lahtinen@linux.intel.com
    (cherry picked from commit f6d4afc9ec6a0bc326151b35a7a3369369180079)
    Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 942f4eed817f..65ce54b20ec2 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -896,7 +896,7 @@ static struct i915_vma *eb_lookup_vma(struct i915_execbuffer *eb, u32 handle)

 		rcu_read_lock();
 		vma = radix_tree_lookup(&eb->gem_context->handles_vma, handle);
-		if (likely(vma && vma->vm == vm))
+		if (likely(vma))
 			vma = i915_vma_tryget(vma);
 		else
 			vma = NULL;