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xen/gntdev: Ignore failure to unmap INVALID_GRANT_HANDLE 

The error paths of gntdev_mmap() can call unmap_grant_pages() even
though not all of the pages have been successfully mapped.  This will
trigger the WARN_ON()s in __unmap_grant_pages_done().  The number of
warnings can be very large; I have observed thousands of lines of
warnings in the systemd journal.

Avoid this problem by only warning on unmapping failure if the handle
being unmapped is not INVALID_GRANT_HANDLE.  The handle field of any
page that was not successfully mapped will be INVALID_GRANT_HANDLE, so
this catches all cases where unmapping can legitimately fail.

Fixes: dbe97cff7d ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
Cc: stable@vger.kernel.org
Suggested-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220710230522.1563-1-demi@invisiblethingslab.com
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Demi Marie Obenour 2022-07-10 19:05:22 -04:00 committed by Juergen Gross
parent dbe97cff7d
commit 166d386323
1 changed files with 4 additions and 2 deletions
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6
drivers/xen/gntdev.c
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@ -396,13 +396,15 @@ static void __unmap_grant_pages_done(int result,
unsigned int offset = data->unmap_ops - map->unmap_ops; unsigned int offset = data->unmap_ops - map->unmap_ops;
for (i = 0; i < data->count; i++) { for (i = 0; i < data->count; i++) {
WARN_ON(map->unmap_ops[offset+i].status); WARN_ON(map->unmap_ops[offset + i].status != GNTST_okay &&
map->unmap_ops[offset + i].handle != INVALID_GRANT_HANDLE);
pr_debug("unmap handle=%d st=%d\n", pr_debug("unmap handle=%d st=%d\n",
map->unmap_ops[offset+i].handle, map->unmap_ops[offset+i].handle,
map->unmap_ops[offset+i].status); map->unmap_ops[offset+i].status);
map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE; map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
if (use_ptemod) { if (use_ptemod) {
WARN_ON(map->kunmap_ops[offset+i].status); WARN_ON(map->kunmap_ops[offset + i].status != GNTST_okay &&
map->kunmap_ops[offset + i].handle != INVALID_GRANT_HANDLE);
pr_debug("kunmap handle=%u st=%d\n", pr_debug("kunmap handle=%u st=%d\n",
map->kunmap_ops[offset+i].handle, map->kunmap_ops[offset+i].handle,
map->kunmap_ops[offset+i].status); map->kunmap_ops[offset+i].status);