On Mon, Mar 12, 2018 at 7:17 AM, Jerome Glisse <jglisse@xxxxxxxxxx> wrote: > On Fri, Mar 09, 2018 at 10:55:26PM -0800, Dan Williams wrote: >> The HMM sub-system extended dev_pagemap to arrange a callback when a >> dev_pagemap managed page is freed. Since a dev_pagemap page is free / >> idle when its reference count is 1 it requires an additional branch to >> check the page-type at put_page() time. Given put_page() is a hot-path >> we do not want to incur that check if HMM is not in use, so a static >> branch is used to avoid that overhead when not necessary. >> >> Now, the FS_DAX implementation wants to reuse this mechanism for >> receiving dev_pagemap ->page_free() callbacks. Rework the HMM-specific >> static-key into a generic mechanism that either HMM or FS_DAX code paths >> can enable. > > Why EXPORT_SYMBOL_GPL and not EXPORT_SYMBOL like it was prior to this > patch ? Not i care that much about that, just wondering. Maybe keep it > EXPORT_SYMBOL() ? HMM has significant integrations and useful hacks within the mm sub-system, I think we should go further than just these symbols and also include devm_memremap_pages() as EXPORT_SYMBOL_GPL. It was simply an oversight that these were EXPORT_SYMBOL previously. > In any case > Reviewed-by: "Jérôme Glisse" <jglisse@xxxxxxxxxx> Thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
