From: Danilo Krummrich <dakr@kernel.org>
Date: Tue, 30 Jul 2024 18:49:42 +0000 (+0200)
Subject: mm: vrealloc: consider spare memory for __GFP_ZERO
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=ff4675c58f8cbbb3c2be7512466105d764224055;p=users%2Fjedix%2Flinux-maple.git

mm: vrealloc: consider spare memory for __GFP_ZERO

Zero spare memory when shrinking a buffer with __GFP_ZERO.

Link: https://lkml.kernel.org/r/20240730185049.6244-3-dakr@kernel.org
Fixes: 1f39ee9615a8 ("mm: vmalloc: implement vrealloc()")
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f364bba9a5cb..4339c56be3c8 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -4070,12 +4070,15 @@ void *vrealloc_noprof(const void *p, size_t size, gfp_t flags)
 		old_size = get_vm_area_size(vm);
 	}
 
+	/*
+	 * TODO: Shrink the vm_area, i.e. unmap and free unused pages. What
+	 * would be a good heuristic for when to shrink the vm_area?
+	 */
 	if (size <= old_size) {
-		/*
-		 * TODO: Shrink the vm_area, i.e. unmap and free unused pages.
-		 * What would be a good heuristic for when to shrink the
-		 * vm_area?
-		 */
+		/* Zero out spare memory. */
+		if (want_init_on_alloc(flags))
+			memset((void *)p + size, 0, old_size - size);
+
 		return (void *)p;
 	}