On 06/13/2018 12:51 PM, Dan Williams wrote: > [ adding Andrew, Christoph, and linux-mm ] > > On Wed, Jun 13, 2018 at 12:33 PM, Joe Gorse <jhgorse@xxxxxxxxx> wrote: >> Greetings, >> >> Please CC answers & comments to this email. Thanks! =) >> >> Our build is breaking as of >> commit e7638488434415aa478e78435cac8f0365737638 >> Author: Dan Williams <dan.j.williams@xxxxxxxxx> >> Date: Wed May 16 11:46:08 2018 -0700 >> >> mm: introduce MEMORY_DEVICE_FS_DAX and CONFIG_DEV_PAGEMAP_OPS >> ... snip ... >> https://patchwork.kernel.org/patch/10412459/ >> >> We do not directly use the GPL-only symbol '__put_devmap_managed_page'. It >> appears to be picked up from static-inlining in put_page(), which we need. >> >> How shall we proceed? Would it be reasonable to request the change of the >> GPL-only exports for this commit? >> >> Cheers, >> Joe Gorse >> >> P.S. The build failure, for the morbidly curious: >>> FATAL: modpost: GPL-incompatible module libafs.ko uses GPL-only symbol >>> '__put_devmap_managed_page' >>> scripts/Makefile.modpost:92: recipe for target '__modpost' failed >>> make[6]: *** [__modpost] Error 1 > > I think the right answer here is to make __put_devmap_managed_page() > EXPORT_SYMBOL(), since features like devm_memremap_pages() want to > change the behavior of all users of put_page(). It again holds that > devm_memremap_pages() needs to become EXPORT_SYMBOL_GPL() because it, > not put_page(), is the interface that is leaking control of core > kernel state/infrastructure to its users. > Hi Dan and all, It looks like put_page() also picks up one more GPL symbol: devmap_managed_key. put_page put_devmap_managed_page devmap_managed_key __put_devmap_managed_page So if the goal is to restore put_page() to be effectively EXPORT_SYMBOL again, then I think there would also need to be either a non-inlined wrapper for devmap_managed_key (awkward for a static key), or else make it EXPORT_SYMBOL, or maybe something else that's less obvious to me at the moment. thanks, -- John Hubbard NVIDIA
