| Message ID | 20220710230522.1563-1-demi@invisiblethingslab.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 166d3863231667c4f64dee72b77d1102cdfad11f |
| Headers | show |
| Series | [v3] xen/gntdev: Ignore failure to unmap INVALID_GRANT_HANDLE | expand |
On 11.07.22 02:05, Demi Marie Obenour wrote: Hello Demi Marie > 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. > > Suggested-by: Juergen Gross <jgross@suse.com> > Cc: stable@vger.kernel.org > Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com> > Fixes: dbe97cff7dd9 ("xen/gntdev: Avoid blocking in unmap_grant_pages()") Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> > --- > drivers/xen/gntdev.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > Changes since v2: > > - Use unmap_ops instead of kunmap_ops in the first WARN_ON > > Changes since v1: > > - Explicitly check for a status other than GNTST_okay instead of > implicitly checking that it is nonzero. > - Avoid wrapping a line as within a comparison, as this makes the code > hard to read. > > diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c > index 4b56c39f766d4da68570d08d963f6ef40c8d9c37..84b143eef395b1585f3a8c0fdcb301ce9fbc52ec 100644 > --- a/drivers/xen/gntdev.c > +++ b/drivers/xen/gntdev.c > @@ -396,13 +396,15 @@ static void __unmap_grant_pages_done(int result, > unsigned int offset = data->unmap_ops - map->unmap_ops; > > 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", > map->unmap_ops[offset+i].handle, > map->unmap_ops[offset+i].status); > map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE; > 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", > map->kunmap_ops[offset+i].handle, > map->kunmap_ops[offset+i].status);
On 11.07.22 01:05, Demi Marie Obenour wrote: > 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. > > Suggested-by: Juergen Gross <jgross@suse.com> > Cc: stable@vger.kernel.org > Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com> > Fixes: dbe97cff7dd9 ("xen/gntdev: Avoid blocking in unmap_grant_pages()") Reviewed-by: Juergen Gross <jgross@suse.com> Juergen
On 11.07.22 01:05, Demi Marie Obenour wrote: > 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. > > Suggested-by: Juergen Gross <jgross@suse.com> > Cc: stable@vger.kernel.org > Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com> > Fixes: dbe97cff7dd9 ("xen/gntdev: Avoid blocking in unmap_grant_pages()") Pushed to xen/tip.git for-linus-5.19a Juergen
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index 4b56c39f766d4da68570d08d963f6ef40c8d9c37..84b143eef395b1585f3a8c0fdcb301ce9fbc52ec 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -396,13 +396,15 @@ static void __unmap_grant_pages_done(int result, unsigned int offset = data->unmap_ops - map->unmap_ops; 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", map->unmap_ops[offset+i].handle, map->unmap_ops[offset+i].status); map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE; 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", map->kunmap_ops[offset+i].handle, map->kunmap_ops[offset+i].status);
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. Suggested-by: Juergen Gross <jgross@suse.com> Cc: stable@vger.kernel.org Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com> Fixes: dbe97cff7dd9 ("xen/gntdev: Avoid blocking in unmap_grant_pages()") --- drivers/xen/gntdev.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) Changes since v2: - Use unmap_ops instead of kunmap_ops in the first WARN_ON Changes since v1: - Explicitly check for a status other than GNTST_okay instead of implicitly checking that it is nonzero. - Avoid wrapping a line as within a comparison, as this makes the code hard to read.