From 60ae4c62d3b7136f05641cf8989330a1881c8d58 Mon Sep 17 00:00:00 2001
From: klzgrad <kizdiv@gmail.com>
Date: Sat, 12 Nov 2022 15:13:24 +0800
Subject: [PATCH] allocator: Fix recommitted pages not being zeroed when
 madvise is not available.

Support kernels built without CONFIG_ADVISE_SYSCALLS on small
embedded devices.
---
 src/base/allocator/partition_allocator/page_allocator.h        | 2 ++
 .../partition_allocator/page_allocator_internals_posix.h       | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/src/base/allocator/partition_allocator/page_allocator.h b/src/base/allocator/partition_allocator/page_allocator.h
index 8e366cc168..d2fc8d28d3 100644
--- a/src/base/allocator/partition_allocator/page_allocator.h
+++ b/src/base/allocator/partition_allocator/page_allocator.h
@@ -260,6 +260,8 @@ constexpr PA_COMPONENT_EXPORT(
     PARTITION_ALLOC) bool DecommittedMemoryIsAlwaysZeroed() {
 #if BUILDFLAG(IS_APPLE)
   return false;
+#elif defined(NO_MADVISE_SYSCALL)
+  return false;
 #else
   return true;
 #endif
diff --git a/src/base/allocator/partition_allocator/page_allocator_internals_posix.h b/src/base/allocator/partition_allocator/page_allocator_internals_posix.h
index 906cdde069..9916dabfba 100644
--- a/src/base/allocator/partition_allocator/page_allocator_internals_posix.h
+++ b/src/base/allocator/partition_allocator/page_allocator_internals_posix.h
@@ -410,6 +410,9 @@ void DiscardSystemPagesInternal(uintptr_t address, size_t length) {
     ret = madvise(ptr, length, MADV_DONTNEED);
   }
   PA_PCHECK(ret == 0);
+#elif defined(NO_MADVISE_SYSCALL)
+  static_cast<void>(ptr);
+  static_cast<void>(length);
 #else   // BUILDFLAG(IS_APPLE)
   // We have experimented with other flags, but with suboptimal results.
   //