On Sat, Jul 6, 2024 at 3:12 PM Wei Yang <richard.weiyang@xxxxxxxxx> wrote: > > On Fri, Jul 05, 2024 at 06:54:56AM +0000, Wei Yang wrote: > >On Wed, Jul 03, 2024 at 11:44:38PM +0900, Masahiro Yamada wrote: > >>On Wed, Jul 3, 2024 at 8:40 AM Wei Yang <richard.weiyang@xxxxxxxxx> wrote: > >>> > >>> .meminit.* is not put into init section when CONFIG_MEMORY_HOTPLUG is > >>> set, since we define MEM_KEEP()/MEM_DISCARD() according to > >>> CONFIG_MEMORY_HOTPLUG. > >>> > >>> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx> > >>> CC: Mike Rapoport (IBM) <rppt@xxxxxxxxxx> > >>> --- > >>> scripts/mod/modpost.c | 10 ++++++++++ > >>> 1 file changed, 10 insertions(+) > >> > >> > >> > >>NACK. > >> > >> > >>The section mismatch is performed _unconditionally_. > >> > >> > >> > >>In the old days, we did this depending on relevant CONFIG options. > >>It was more than 15 years ago that we stopped doing that. > >> > >> > >>See this: > >> > >> > >>commit eb8f689046b857874e964463619f09df06d59fad > >>Author: Sam Ravnborg <sam@xxxxxxxxxxxx> > >>Date: Sun Jan 20 20:07:28 2008 +0100 > >> > >> Use separate sections for __dev/__cpu/__mem code/data > >> > >> > >> > >> > >>So, if you wanted to check this only when CONFIG_MEMORY_HOTPLUG=n, > >>you would need to add #ifdef CONFIG_MEMORY_HOTPLUG to include/linux/init.h > >> > >>That is what we did in the Linux 2.6.* era, which had much worse > >>section mismatch coverage. > >> > > > >Masahiro > > > >If you would give me some suggestions, I'd appreciate it a lot. > > > >The original thing I want to do is to put function __free_pages_core() in > >__meminit section, since this function is only used by __init functions and > >in memory_hotplug.c. This means it is save to release it if > >CONFIG_MEMORY_HOTPLUG is set. > > > >Then I add __meminit to function __free_pages_core() and face the warning from > >modpost. > > > > WARNING: modpost: vmlinux: section mismatch in reference: generic_online_page+0xa (section: .text) -> __free_pages_core (section: .meminit.text) > > > >A .text function calls init code is not proper. Then I add __meminit to > >generic_online_page too. Then I face this warning from modpost. > > > > WARNING: modpost: vmlinux: generic_online_page: EXPORT_SYMBOL used for init symbol. Remove __init or EXPORT_SYMBOL. > > > > I guess I found the correct way. > > Add __ref to generic_online_page to not issue a warning. Yes, __ref is used to bypass the section mismatch check. Some functions in mm/memory_hotplug.c are annotated as __ref to reference __meminit functions. Adding __ref is the easy solution. Having said that, I started to think eb8f689046b857874e964463619f09df06d59fad was the wrong decision. I will revert it. -- Best Regards Masahiro Yamada
