@@ -816,6 +816,13 @@ static inline void arch_swap_restore(swp_entry_t entry, struct folio *folio)
}
#endif
+#ifndef __HAVE_ARCH_SWAP_PREPARE_TO_RESTORE
+static inline int arch_swap_prepare_to_restore(swp_entry_t entry, struct folio *folio)
+{
+ return 0;
+}
+#endif
+
#ifndef __HAVE_ARCH_PGD_OFFSET_GATE
#define pgd_offset_gate(mm, addr) pgd_offset(mm, addr)
#endif
@@ -3724,6 +3724,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
swp_entry_t entry;
pte_t pte;
int locked;
+ int error;
vm_fault_t ret = 0;
void *shadow = NULL;
@@ -3892,6 +3893,16 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
folio_throttle_swaprate(folio, GFP_KERNEL);
+ /*
+ * Some architecture may need to perform certain operations before
+ * arch_swap_restore() in preemptible context (like memory allocations).
+ */
+ error = arch_swap_prepare_to_restore(entry, folio);
+ if (error) {
+ ret = VM_FAULT_ERROR;
+ goto out_page;
+ }
+
/*
* Back out if somebody else already faulted in this pte.
*/
@@ -1796,6 +1796,10 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
}
folio_wait_writeback(folio);
+ error = arch_swap_prepare_to_restore(swap, folio);
+ if (error)
+ goto unlock;
+
/*
* Some architectures may have to restore extra metadata to the
* folio after reading from swap.
@@ -1756,6 +1756,10 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
else if (unlikely(PTR_ERR(page) == -EHWPOISON))
hwposioned = true;
+ ret = arch_swap_prepare_to_restore(entry, folio);
+ if (ret)
+ return ret;
+
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
if (unlikely(!pte || !pte_same_as_swp(ptep_get(pte),
swp_entry_to_pte(entry)))) {
arch_swap_restore() allows an architecture to restore metadata before the page is swapped in and it's called in atomic context (with the ptl lock held). Introduce arch_swap_prepare_to_restore() to allow such architectures to perform extra work in a blocking context. Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com> --- include/linux/pgtable.h | 7 +++++++ mm/memory.c | 11 +++++++++++ mm/shmem.c | 4 ++++ mm/swapfile.c | 4 ++++ 4 files changed, 26 insertions(+)