On Sat, Jul 06, 2024 at 10:50:25PM +0900, Masahiro Yamada wrote: >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. > I am think whether __ref is providing a gate to escape the check of modpost? >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. > Oh, I finally understand it... didn't think that was a wrong decision :-( > > > > > > > > > > >-- >Best Regards >Masahiro Yamada -- Wei Yang Help you, Help me
