[DRBD-user] drbd 9.0.26 and newer fails to build on 5.4 kernels
Natanael Copa
ncopa at alpinelinux.org
Tue Feb 23 11:17:27 CET 2021
On Mon, 22 Feb 2021 12:37:41 +0100
Christoph Böhmwalder <christoph.boehmwalder at linbit.com> wrote:
> On 2/22/21 11:40 AM, Natanael Copa wrote:
> > On Fri, 19 Feb 2021 19:50:13 +0100
> > Natanael Copa <ncopa at alpinelinux.org> wrote:
> >
> >> On Fri, 19 Feb 2021 19:38:53 +0100
> >> Natanael Copa <ncopa at alpinelinux.org> wrote:
> >>
> >>> Hi,
> >>>
> >>> I tried to update the kernel for alpine 3.12-stable branch from 5.4.84
> >>> to 5.4.99. The 3rd part kernel module drbd 9.0.22-2 failed to build so
> >>> I updated it to 9.0.27-1. This passed on the x86_64 machine I tested
> >>> built it on so I pushed it.
> >>>
> >>> But it failed on 32 bit arm builders:
> >>>
> >>> ...
> >>> In file included from ./include/linux/module.h:27,
> >>> from /home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd_req.h:16,
> >>> from /home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd_state.c:22:
> >>> ./arch/arm/include/asm/module.h:59: warning: "MODULE_ARCH_VERMAGIC" redefined
> >>> 59 | #define MODULE_ARCH_VERMAGIC \
> >>> |
> >>> In file included from /home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd_state.c:19:
> >>> ./include/linux/vermagic.h:28: note: this is the location of the previous definition
> >>> 28 | #define MODULE_ARCH_VERMAGIC ""
> >>> |
> >>> GEN /home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd_buildtag.c
> >>> CC [M] /home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd_buildtag.o
> >>> LD [M] /home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd.o
> >>> Building modules, stage 2.
> >>> MODPOST 2 modules
> >>> ERROR: "__aeabi_ldivmod" [/home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd.ko] undefined!
> >>> ERROR: "__aeabi_uldivmod" [/home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd.ko] undefined!
> >>> make[3]: *** [scripts/Makefile.modpost:94: __modpost] Error 1
> >>> make[2]: *** [Makefile:1639: modules] Error 2
> >>> make[1]: *** [Makefile:132: kbuild] Error 2
> >>> make[1]: Leaving directory '/home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd'
> >>> make: *** [Makefile:131: module] Error 2
> >>>>>> ERROR: drbd-lts: build failed
> >>>
> >>> And on 32 bit x86:
> >>>
> >>> GEN /home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd_buildtag.c
> >>> CC [M] /home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd_buildtag.o
> >>> LD [M] /home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd.o
> >>> Building modules, stage 2.
> >>> MODPOST 2 modules
> >>> ERROR: "__udivdi3" [/home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd.ko] undefined!
> >>> ERROR: "__divdi3" [/home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd/drbd.ko] undefined!
> >>> make[3]: *** [scripts/Makefile.modpost:94: __modpost] Error 1
> >>> make[2]: *** [Makefile:1639: modules] Error 2
> >>> make[1]: *** [Makefile:132: kbuild] Error 2
> >>> make[1]: Leaving directory '/home/buildozer/aports/main/drbd-lts/src/drbd-9.0.27-1/drbd'
> >>> make: *** [Makefile:131: module] Error 2
> >>>>>> ERROR: drbd-lts: build failed
> >>>
> >>> I read that this can happen if do_div() is not used and libgcc is not
> >>> linked in (which I assume we shouldnt on kernel). I tried to look at
> >>> the git log if I could find anything evident but couldn't find anything.
> >>>
> >>> So I tried to find older version. Turns out that the lastest version
> >>> that compiles with 5.4 kernel is 9.0.25-2, but it only compiles with
> >>> 5.4.84 kernel and not the 5.4.99.
> >>>
> >>> Does anyone have a clue how to solve this? If not, I guess I have to
> >>> try git bisect it.
> >
> >
> > I found the commit that introduces the issue using objdump and git log:
> >
> > commit 8dc8ede32de4410e99148b39d0f960e975eeddea
> > Author: Joel Colledge <joel.colledge at linbit.com>
> > Date: Wed Nov 11 18:11:26 2020 +0100
> >
> > drbd: fix slow sync when sync requests are answered quickly
> >
> >
> > It is the DIV_ROUND_UP in that commit that introduces this.
> >
> > This change fixes it:
> > diff --git a/drbd/drbd_sender.c b/drbd/drbd_sender.c
> > index 30e301fb..34030870 100644
> > --- a/drbd/drbd_sender.c
> > +++ b/drbd/drbd_sender.c
> > @@ -687,7 +687,7 @@ static int drbd_resync_delay(struct drbd_peer_device *peer_device)
> > * that the rate limiting prevents any new requests
> > * from being made. Wait just long enough so that we
> > * can request some data next time. */
> > - delay = DIV_ROUND_UP(HZ * BM_SECT_PER_BIT, pdc->c_max_rate * 2);
> > + delay = DIV_ROUND_UP((unsigned long)(HZ * BM_SECT_PER_BIT / 2), pdc->c_max_rate);
> > }
> > } else {
> > /* Fixed resync rate. Use the standard delay. */
> >
> >
> > As I understand, it is the compiler that converts the HZ *
> > BM_SECT_PER_BIT to 64 bit type which triggers the error.
> >
> > As I understand the source BM_SECT_PER_BIT = 1 << (12-9) = 8, so it
> > should be safe to move the `* 2` on the right side to a `/ 2` on the
> > left, which results in HZ * 4 / pdc->c_max_rate.
> >
> > HZ is to my understand seldomly (never?) set to anything above 1000?
> > And 1000 * 4 fits just fine in an unsigned long, so I think the above diff should be safe.
> >
> > -nc
> > _______________________________________________
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> > drbd-user at lists.linbit.com
> > https://lists.linbit.com/mailman/listinfo/drbd-user
> >
>
> Hi Natanael,
>
> thanks for the proposed fix! Your logic seems right to me.
>
> I have committed it to the drbd repository, along with one other similar
> fix. See
> https://github.com/LINBIT/drbd/commit/4194a136b08c1f204707bdb0695fc05c0b2997e9
Looks good.
> Are you able to test the latest git HEAD (drbd-9.0 branch) on your
> infrastructure to verify that this is fixed for you?
I'm sorry but I cannot build it from git on 32 bit arches due to the
spatch/coccinelle. But I did apply the proposed patch on top of 9.0.27
and it builds at least.
https://git.alpinelinux.org/aports/commit/?h=3.12-stable&id=d18a91093f667669f20812889b6a5580424eb3e1
thanks!
-nc
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