diff options
| author | Shivam Kalra <shivamkalra98@zohomail.in> | 2026-05-19 17:42:16 +0530 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-06-02 15:22:32 -0700 |
| commit | 0bca23804632cc7275fc5f67191b6be58993cd28 (patch) | |
| tree | 8fbe535ccafee90fc990b82e83cadc198069413b /mm | |
| parent | d57ac904ffdce6c06e9a113fce603420c041b48c (diff) | |
mm/vmalloc: use physical page count in vread_iter() for VM_ALLOC areas
For VM_ALLOC areas in vread_iter(), derive the vm area size from
vm->nr_pages rather than get_vm_area_size().
Only VM_ALLOC areas are subject to vrealloc() shrinking, which frees pages
without reducing the virtual reservation size. Switch to using
vm->nr_pages for VM_ALLOC areas so the reader remains correct once shrink
support is added. Other mapping types (vmap, ioremap) do not initialize
nr_pages and will continue using get_vm_area_size().
[shivamkalra98@zohomail.in: add an nr_pages check]
Link: https://lore.kernel.org/aff47da5-4fd5-481d-be18-e1eb99639490@zohomail.in
Link: https://lore.kernel.org/20260519-vmalloc-shrink-v14-3-70b96ee3e9c9@zohomail.in
Signed-off-by: Shivam Kalra <shivamkalra98@zohomail.in>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/vmalloc.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 3e159b74cfab..bc21bf8e188b 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4666,7 +4666,18 @@ long vread_iter(struct iov_iter *iter, const char *addr, size_t count) smp_rmb(); vaddr = (char *) va->va_start; - size = vm ? get_vm_area_size(vm) : va_size(va); + if (vm) + /* + * For VM_ALLOC areas, use nr_pages rather than + * get_vm_area_size() because vrealloc() may shrink + * the mapping without updating area->size. Other + * mapping types (vmap, ioremap) don't set nr_pages. + */ + size = (vm->flags & VM_ALLOC && vm->nr_pages) ? + (vm->nr_pages << PAGE_SHIFT) : + get_vm_area_size(vm); + else + size = va_size(va); if (addr >= vaddr + size) goto next_va; |