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| author | Vasily Gorbik <gor@linux.ibm.com> | 2025-11-28 23:01:05 +0100 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2025-12-07 16:15:19 +0100 |
| commit | 6a35d02fec5a1e2ab6c0c94ccc5b0c57a580b098 (patch) | |
| tree | b52b25e9b8bfc537485330acd65b05777766f8b1 | |
| parent | 1442bb87b878f889442c7e8e83d9125e31ef5072 (diff) | |
| download | linux-6a35d02fec5a1e2ab6c0c94ccc5b0c57a580b098.tar.gz | |
s390/vmem: Support 2G page splitting for KASAN shadow freeing
Export split_pud_page() so it can be used from the vmem code and teach
modify_pud_table() to split PUD-sized mappings when only a subrange
needs to be removed.
If the range to be removed covers a full PUD-sized mapping, keep the
existing behavior: clear the PUD entry and free the backing large page
(for non-direct mappings). Otherwise, split the PUD-mapped page into
PMD mappings and let the walker handle the smaller ranges.
This is needed for KASAN early shadow removal support: memory hotplug
freeing the KASAN early shadow is the only expected caller that will
try to free 2G PUD-mapped regions of non-direct mappings.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
| -rw-r--r-- | arch/s390/include/asm/page.h | 2 | ||||
| -rw-r--r-- | arch/s390/mm/pageattr.c | 2 | ||||
| -rw-r--r-- | arch/s390/mm/vmem.c | 6 |
3 files changed, 8 insertions, 2 deletions
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h index 9240a363c89355..c1d63b613bf9bf 100644 --- a/arch/s390/include/asm/page.h +++ b/arch/s390/include/asm/page.h @@ -166,6 +166,8 @@ static inline int page_reset_referenced(unsigned long addr) return CC_TRANSFORM(cc); } +int split_pud_page(pud_t *pudp, unsigned long addr); + /* Bits int the storage key */ #define _PAGE_CHANGED 0x02 /* HW changed bit */ #define _PAGE_REFERENCED 0x04 /* HW referenced bit */ diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c index 3042647c9dbf4e..d3ce04a4b24864 100644 --- a/arch/s390/mm/pageattr.c +++ b/arch/s390/mm/pageattr.c @@ -204,7 +204,7 @@ static int walk_pmd_level(pud_t *pudp, unsigned long addr, unsigned long end, return rc; } -static int split_pud_page(pud_t *pudp, unsigned long addr) +int split_pud_page(pud_t *pudp, unsigned long addr) { unsigned long pmd_addr, prot; pmd_t *pm_dir, *pmdp; diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c index d96587b84e81f5..faed09531499b1 100644 --- a/arch/s390/mm/vmem.c +++ b/arch/s390/mm/vmem.c @@ -330,10 +330,14 @@ static int modify_pud_table(p4d_t *p4d, unsigned long addr, unsigned long end, if (pud_leaf(*pud)) { if (IS_ALIGNED(addr, PUD_SIZE) && IS_ALIGNED(next, PUD_SIZE)) { + if (!direct) + vmem_free_pages(pud_deref(*pud), get_order(PUD_SIZE), altmap); pud_clear(pud); pages++; + continue; + } else { + split_pud_page(pud, addr & PUD_MASK); } - continue; } } else if (pud_none(*pud)) { if (IS_ALIGNED(addr, PUD_SIZE) && |