On 9/27/2024 11:58 AM, Jason Gunthorpe wrote:
On Fri, Sep 27, 2024 at 05:44:52PM +0200, David Hildenbrand wrote:/** * folio_try_add_pins() - add pins to an already-pinned folio * @folio: the folio to add more pins to * * Try to add more pins to an already-pinned folio. The semantics * of the pin (e.g., FOLL_WRITE) follow any existing pin and cannot * be changed. * * This function is helpful when having obtained a pin on a large folio * using memfd_pin_folios(), but wanting to logically unpin parts * (e.g., individual pages) of the folio later, for example, using * unpin_user_page_range_dirty_lock(). * * This is not the right interface to initially pin a folio. */ int folio_try_add_pins(struct folio *folio, unsigned int pins) { VM_WARN_ON_ONCE(!folio_maybe_dma_pinned(folio)); return try_grab_folio(folio, pins, FOLL_PIN); }That looks pretty good to me too
Looks good and passes my tests, I will add this version in V3 of the patch series. Are you sure you want "try" in the name folio_try_add_pins? Usually try means that any failure is transient and a future call may succeed, but the failures in try_grab_folio look permanent to me (suggesting that is also a misnomer, but at least it is not exported). - Steve
