From: Balbir Singh <balbirs@nvidia•com>
To: Claudio Imbrenda <imbrenda@linux•ibm.com>, akpm@linux-foundation•org
Cc: borntraeger@de•ibm.com, david@redhat•com,
Liam.Howlett@oracle•com, airlied@gmail•com, apopple@nvidia•com,
baohua@kernel•org, baolin.wang@linux•alibaba.com,
byungchul@sk•com, dakr@kernel•org, dev.jain@arm•com,
dri-devel@lists•freedesktop.org, francois.dugast@intel•com,
gourry@gourry•net, joshua.hahnjy@gmail•com,
linux-kernel@vger•kernel.org, linux-mm@kvack•org,
lorenzo.stoakes@oracle•com, lyude@redhat•com,
matthew.brost@intel•com, mpenttil@redhat•com, npache@redhat•com,
osalvador@suse•de, rakie.kim@sk•com, rcampbell@nvidia•com,
ryan.roberts@arm•com, simona@ffwll•ch,
ying.huang@linux•alibaba.com, ziy@nvidia•com,
kvm@vger•kernel.org, linux-s390@vger•kernel.org,
linux-next@vger•kernel.org, hca@linux•ibm.com, gor@linux•ibm.com,
agordeev@linux•ibm.com
Subject: Re: [PATCH v1 1/1] KVM: s390: Fix missing present bit for gmap puds
Date: Wed, 29 Oct 2025 08:23:20 +1100 [thread overview]
Message-ID: <99fd44ff-85bb-4892-90f3-381843feccab@nvidia.com> (raw)
In-Reply-To: <20251028130150.57379-2-imbrenda@linux.ibm.com>
On 10/29/25 00:01, Claudio Imbrenda wrote:
> For hugetlbs, gmap puds have the present bit set. For normal puds
> (which point to ptes), the bit is not set. This is in contrast to the
> normal userspace puds, which always have the bit set for present pmds.
>
> This causes issues when ___pte_offset_map() is modified to only check
> for the present bit.
>
> The solution to the problem is simply to always set the present bit for
> present gmap pmds.
>
> Signed-off-by: Claudio Imbrenda <imbrenda@linux•ibm.com>
> Link: https://lore.kernel.org/lkml/20251017144924.10034-1-borntraeger@linux.ibm.com/
> Tested-by: Christian Borntraeger <borntraeger@linux•ibm.com>
> Acked-by: Christian Borntraeger <borntraeger@linux•ibm.com>
> ---
> arch/s390/mm/gmap.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index 8ff6bba107e8..22c448b32340 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -599,8 +599,9 @@ int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
> | _SEGMENT_ENTRY_GMAP_UC
> | _SEGMENT_ENTRY;
> } else
> - *table = pmd_val(*pmd) &
> - _SEGMENT_ENTRY_HARDWARE_BITS;
> + *table = (pmd_val(*pmd) &
> + _SEGMENT_ENTRY_HARDWARE_BITS)
> + | _SEGMENT_ENTRY;
> }
> } else if (*table & _SEGMENT_ENTRY_PROTECT &&
> !(pmd_val(*pmd) & _SEGMENT_ENTRY_PROTECT)) {
Acked-by: Balbir Singh <balbirs@nvidia•com>
next prev parent reply other threads:[~2025-10-28 21:23 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20251001065707.920170-4-balbirs@nvidia.com>
2025-10-17 14:49 ` linux-next: KVM/s390x regression (was: [v7 03/16] mm/huge_memory: add device-private THP support to PMD operations) Christian Borntraeger
2025-10-17 14:54 ` linux-next: KVM/s390x regression David Hildenbrand
2025-10-17 15:01 ` Christian Borntraeger
2025-10-17 15:07 ` David Hildenbrand
2025-10-17 15:20 ` Christian Borntraeger
2025-10-17 17:07 ` David Hildenbrand
2025-10-17 21:56 ` Balbir Singh
2025-10-17 22:15 ` David Hildenbrand
2025-10-17 22:41 ` David Hildenbrand
2025-10-20 7:01 ` Christian Borntraeger
2025-10-20 7:00 ` Christian Borntraeger
2025-10-20 8:41 ` David Hildenbrand
2025-10-20 9:04 ` Claudio Imbrenda
2025-10-27 16:47 ` Claudio Imbrenda
2025-10-27 16:59 ` David Hildenbrand
2025-10-27 17:06 ` Christian Borntraeger
2025-10-28 9:24 ` Balbir Singh
2025-10-28 13:01 ` [PATCH v1 0/1] KVM: s390: Fix missing present bit for gmap puds Claudio Imbrenda
2025-10-28 13:01 ` [PATCH v1 1/1] " Claudio Imbrenda
2025-10-28 21:23 ` Balbir Singh [this message]
2025-10-29 10:00 ` David Hildenbrand
2025-10-29 10:20 ` Claudio Imbrenda
2025-10-28 22:53 ` [PATCH v1 0/1] " Andrew Morton
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