diff options
| author | Gautam Gala <ggala@linux.ibm.com> | 2025-09-24 13:26:44 +0200 |
|---|---|---|
| committer | Claudio Imbrenda <imbrenda@linux.ibm.com> | 2025-09-30 15:58:30 +0200 |
| commit | 5deafa27d9ae040b75d392f60b12e300b42b4792 (patch) | |
| tree | 8171f615eceb121afc3184ba3b367e127d21d326 /arch/s390/mm/gmap_helpers.c | |
| parent | 352ccf890a3e91f58bc32503f9afdc161bc2c34a (diff) | |
KVM: s390: Fix to clear PTE when discarding a swapped page
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: 200197908dc4 ("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>
Diffstat (limited to 'arch/s390/mm/gmap_helpers.c')
| -rw-r--r-- | arch/s390/mm/gmap_helpers.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/s390/mm/gmap_helpers.c b/arch/s390/mm/gmap_helpers.c index a45d417ad951..c382005577bd 100644 --- a/arch/s390/mm/gmap_helpers.c +++ b/arch/s390/mm/gmap_helpers.c @@ -13,6 +13,7 @@ #include <linux/pagewalk.h> #include <linux/ksm.h> #include <asm/gmap_helpers.h> +#include <asm/pgtable.h> /** * ptep_zap_swap_entry() - discard a swap entry. @@ -45,6 +46,7 @@ void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr) { struct vm_area_struct *vma; spinlock_t *ptl; + pgste_t pgste; pte_t *ptep; mmap_assert_locked(mm); @@ -58,8 +60,16 @@ void gmap_helper_zap_one_page(struct mm_struct *mm, unsigned long vmaddr) ptep = get_locked_pte(mm, vmaddr, &ptl); if (unlikely(!ptep)) return; - if (pte_swap(*ptep)) + if (pte_swap(*ptep)) { + preempt_disable(); + pgste = pgste_get_lock(ptep); + ptep_zap_swap_entry(mm, pte_to_swp_entry(*ptep)); + pte_clear(mm, vmaddr, ptep); + + pgste_set_unlock(ptep, pgste); + preempt_enable(); + } pte_unmap_unlock(ptep, ptl); } EXPORT_SYMBOL_GPL(gmap_helper_zap_one_page); |