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drm/xe/vm: don't ignore error when in_kthread

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If GUP fails and we are in_kthread, we can have pinned = 0 and ret = 0.
If that happens we call sg_alloc_append_table_from_pages() with n_pages
= 0, which is not well behaved and can trigger:

kernel BUG at include/linux/scatterlist.h:115!

depending on if the pages array happens to be zeroed or not. Even if we
don't hit that it crashes later when trying to dma_map the returned
table.

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240202171435.427630-2-matthew.auld@intel.com
(cherry picked from commit 8087199cd5951c1eba26003b3e4296dbb2110adf)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
This commit is contained in:
Matthew Auld 2024-02-02 17:14:36 +00:00 committed by Thomas Hellström
parent 95c058c8ef
commit 9e3fc1d65d
1 changed files with 1 additions and 4 deletions
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5
drivers/gpu/drm/xe/xe_vm.c
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@ -114,11 +114,8 @@ retry:
num_pages - pinned,
read_only ? 0 : FOLL_WRITE,
&pages[pinned]);
if (ret < 0) {
if (in_kthread)
ret = 0;
if (ret < 0)
break;
}
pinned += ret;
ret = 0;