Regression on linux-next (next-20250321)

[Josh Poimboeuf]

On Tue, Mar 25, 2025 at 10:43:17AM -0300, Jason Gunthorpe wrote:
> On Tue, Mar 25, 2025 at 12:40:16AM -0700, Nicolin Chen wrote:
> > 
> > On Tue, Mar 25, 2025 at 05:39:39AM +0000, Borah, Chaitanya Kumar wrote:
> > > Hello Nicolin,
> > > 
> > > Hope you are doing well. I am Chaitanya from the linux graphics team in Intel.
> > > 
> > > This mail is regarding a regression we are seeing in our CI runs[1] on linux-next repository.
> > > 
> > > Since the version next-20250321 [2], we are seeing the following regression
> > > 
> > > `````````````````````````````````````````````````````````````````````````````````
> > > <4>[    0.226495] Unpatched return thunk in use. This should not happen!
> > > <4>[    0.226502] WARNING: CPU: 0 PID: 1 at arch/x86/kernel/cpu/bugs.c:3107 __warn_thunk+0x62/0x70
> > 
> > Hmm....I wonder why x86 can be affected...
> 
> I wonder if this is realted to the objtool warning Steven reported:
> 
> https://lore.kernel.org/linux-next/20250321193600.2bfe03bb@canb.auug.org.au/
> 
> vmlinux.o: warning: objtool: iommu_dma_get_msi_page() falls through to next function __iommu_dma_unmap()
> 
> I have no idea what either error means or how to fix it. AFAICT there
> is nothing special about this patch to trigger this?

Yeah, I'm fairly sure the boot warning is related to that objtool
warning.  I just posted a patch for that:

  https://lore.kernel.org/0c801ae017ec078cacd39f8f0898fc7780535f85.1743053325.git.jpoimboe@kernel.org

But also, we need to fix objtool to handle that warning more gracefully
so it doesn't trigger the boot failure.

-- 
Josh