Re: [PATCH v6] mm/hugetlb: ignore hugepage kernel args if hugepages are unsupported

[Christophe Leroy (CS GROUP)]

Le 22/12/2025 à 11:28, David Hildenbrand (Red Hat) a écrit :
> On 12/22/25 06:57, Sourabh Jain wrote:
> > On 22/12/25 08:42, Ritesh Harjani (IBM) wrote:
> > > "David Hildenbrand (Red Hat)" <david@xxxxxxxxxx> writes:
> > >
> > > > > Coming back to the fixes tag. I did mention a bit of a history [2] of
> > > > > whatever I could find while reviewing this patch. I am not sure 
> > > > > whether
> > > > > you have looked into the links shared in that email or not. Here [2]:
> > > > >
> > > > > [2]: https://eur01.safelinks.protection.outlook.com/? 
> > > > > url=https%3A%2F%2Flore.kernel.org%2Flinuxppc- 
> > > > > dev%2F875xa3ksz9.ritesh.list%40gmail.com%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7Cfe40f4881e8441ab3ebf08de4144e747%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639019961377096292%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=Dnvzy5kJ%2ByF9GJjIw%2B12FTjaVgeAM2gA9g7hsYl7Qok%3D&reserved=0
> > > > >
> > > > > Where I am coming from is.. The current patch is acutally a partial
> > > > > revert of the patch mentioned in the fixes tag. That means if this 
> > > > > patch
> > > > > gets applied to the older stable kernels, it would end up bringing the
> > > > > same problem back, which the "Fixes" tagged patch is fixing in the 1st
> > > > > place, isnt' it? See this discussion [3]...
> > > > >
> > > > > [3]: https://eur01.safelinks.protection.outlook.com/? 
> > > > > url=https%3A%2F%2Flore.kernel.org%2Fall%2Fb1f04f9f-fa46- 
> > > > > c2a0-7693-4a0679d2a1ee%40oracle.com%2FT%2F%23m0eee87b458d93559426b8b0e78dc6ebcd26ad3ae&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7Cfe40f4881e8441ab3ebf08de4144e747%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639019961377117150%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=bOO7FGN4jAtX3jjBnJVpSurmM9rGmz8vIs1iGtbm1gU%3D&reserved=0
> > > > >
> > > > > ... So, IMO - the right fixes tag, if we have to add, it should be the
> > > > > patch which moved the hpage_shift initialization to happen early 
> > > > > i.e. in
> > > > > mmu_early_init_devtree. That would be this patch [4]:
> > > > >
> > > > > [4]: https://eur01.safelinks.protection.outlook.com/? 
> > > > > url=https%3A%2F%2Fgit.kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Ftorvalds%2Flinux.git%2Fcommit%2F%3Fid%3D2354ad252b66695be02f4acd18e37bf6264f0464&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7Cfe40f4881e8441ab3ebf08de4144e747%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639019961377133860%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=0yTuECy%2BBGDLiSNYuqYH9xGBOSxiRLxAtW%2FWTQU%2FB%2BA%3D&reserved=0
> > > > >
> > > > > Now, it's not really that the patch [4] had any issue as such. But it
> > > > > seems like, that the current fix can only be applied after patch 
> > > > > [4] is
> > > > > taken.
> > > > >
> > > > > Do we agree?
> > > > I think we should document all that in the cover letter, an describe
> > > > that this partial revert is only possible after [4],
> > > Yes, I agree. Let's add the above details in the commit msg.
> > >
> > > > and that that must
> > > > be considered when attempting any kind of stable backports.
> > > Sure. I would prefer if we change the Fixes tag to the one which I
> > > pointed in above [4] (with explaination in the commit msg). However I am
> > > still ok if we would like to retain the existing fixes tag and show [4]
> > > as a dependency.
> >
> > I think we should keep the current Fixes tag with an explanation for
> > dependency
> > on [1] in the commit message.
> >
> > Would anyone have a different view?
>
> Whatever introduced the issue should be called out in the Fixes tag; if 
> there are dependencies for the fix through other patches that were 
> already merged, that can be documented in the patch description 
> (relevant for stable or distro backports only).

We can also use the Depends-on: tag, see for exemple commit 9517b82d8d42 
("nbd: defer config put in recv_work"):

    Reported-by: syzbot+56fbf4c7ddf65e95c7cc@xxxxxxxxxxxxxxxxxxxxxxxxx
    Closes: 
https://lore.kernel.org/all/6907edce.a70a0220.37351b.0014.GAE@xxxxxxxxxx/T/
    Fixes: 87aac3a80af5 ("nbd: make the config put is called before the 
notifying the waiter")
    Depends-on: e2daec488c57 ("nbd: Fix hungtask when nbd_config_put")
    Signed-off-by: Zheng Qixing <zhengqixing@xxxxxxxxxx>
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>


Christophe