KVM: s390: Fix to clear PTE when discarding a swapped page

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KVM run fails when guests with 'cmm' cpu feature and host are
under memory pressure and use swap heavily. This is because
npages becomes ENOMEN (out of memory) in hva_to_pfn_slow()
which inturn propagates as EFAULT to qemu. Clearing the page
table entry when discarding an address that maps to a swap
entry resolves the issue.

Fixes: 200197908d ("KVM: s390: Refactor and split some gmap helpers")
Cc: stable@vger.kernel.org
Suggested-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Gautam Gala <ggala@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

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Gautam Gala 2025-09-24 13:26:44 +02:00 • committed by Claudio Imbrenda

parent 352ccf890a

commit 5deafa27d9

3 changed files with 34 additions and 23 deletions

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22

arch/s390/include/asm/pgtable.h

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12

arch/s390/mm/gmap_helpers.c

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23

arch/s390/mm/pgtable.c

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