+ mm-vmalloc-use-physical-page-count-in-vread_iter-for-vm_alloc-areas.patch added to mm-new branch

+ mm-vmalloc-use-physical-page-count-in-vread_iter-for-vm_alloc-areas.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/vmalloc: use physical page count in vread_iter() for VM_ALLOC areas
has been added to the -mm mm-new branch.  Its filename is
     mm-vmalloc-use-physical-page-count-in-vread_iter-for-vm_alloc-areas.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmalloc-use-physical-page-count-in-vread_iter-for-vm_alloc-areas.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Shivam Kalra <shivamkalra98@zohomail.in>
Subject: mm/vmalloc: use physical page count in vread_iter() for VM_ALLOC areas
Date: Tue, 19 May 2026 17:42:16 +0530

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().

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>
---

 mm/vmalloc.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

--- a/mm/vmalloc.c~mm-vmalloc-use-physical-page-count-in-vread_iter-for-vm_alloc-areas
+++ a/mm/vmalloc.c
@@ -4666,7 +4666,18 @@ long vread_iter(struct iov_iter *iter, c
 		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 << PAGE_SHIFT) :
+				       get_vm_area_size(vm);
+		else
+			size = va_size(va);
 
 		if (addr >= vaddr + size)
 			goto next_va;
_

Patches currently in -mm which might be from shivamkalra98@zohomail.in are

mm-vmalloc-extract-vm_area_free_pages-helper-from-vfree.patch
mm-vmalloc-use-physical-page-count-for-vrealloc-grow-in-place-check.patch
mm-vmalloc-use-physical-page-count-in-vread_iter-for-vm_alloc-areas.patch
mm-vmalloc-free-unused-pages-on-vrealloc-shrink.patch
lib-test_vmalloc-add-vrealloc-test-case.patch