[f2fs-dev] [PATCH v2] f2fs_io: adapt w/ page_size in aligned_xalloc()

[f2fs-dev] [PATCH v2] f2fs_io: adapt w/ page_size in aligned_xalloc()

[Chao Yu via Linux-f2fs-devel]

When allocating memory in aligned_xalloc(), if the requested alignment
(e.g., F2FS_DEFAULT_BLKSIZE) is smaller than the system's page size,
aligned_alloc() will allocate memory that is not page-aligned on systems
with 16KB or 64KB page sizes.

As a result, subsequent calls to madvise(..., MADV_HUGEPAGE) will fail
because madvise() requires the memory address and length to be page-aligned.

Fix this by dynamically adjusting the alignment and rounding up the requested
allocation size (via roundup()) to the system's page size, ensuring that
memory is correctly page-aligned for madvise().

Signed-off-by: Chao Yu <chao@kernel.org>
---
 tools/f2fs_io/f2fs_io.c | 17 +++++++++++++++++
 tools/f2fs_io/f2fs_io.h |  3 +++
 2 files changed, 20 insertions(+)

diff --git a/tools/f2fs_io/f2fs_io.c b/tools/f2fs_io/f2fs_io.c
index 94e61b8..9a866cc 100644
--- a/tools/f2fs_io/f2fs_io.c
+++ b/tools/f2fs_io/f2fs_io.c
@@ -97,6 +97,23 @@ static void *xmalloc(size_t size)
 
 static void *aligned_xalloc(size_t alignment, size_t size)
 {
+	long page_size = F2FS_DEFAULT_BLKSIZE;
+
+#ifdef _SC_PAGESIZE
+	page_size = sysconf(_SC_PAGESIZE);
+	if (page_size < 0)
+		page_size = F2FS_DEFAULT_BLKSIZE;
+#endif
+
+	/*
+	 * On systems with large page sizes (e.g., 16KB/64KB), alignment and
+	 * allocation size must be page-aligned to satisfy madvise().
+	 */
+	if (alignment < (size_t)page_size)
+		alignment = page_size;
+
+	size = roundup(size, alignment);
+
 	void *p = aligned_alloc(alignment, size);
 
 	if (!p)
diff --git a/tools/f2fs_io/f2fs_io.h b/tools/f2fs_io/f2fs_io.h
index 539964f..cf1c334 100644
--- a/tools/f2fs_io/f2fs_io.h
+++ b/tools/f2fs_io/f2fs_io.h
@@ -49,6 +49,9 @@ typedef u32	__be32;
 #endif
 
 #define F2FS_DEFAULT_BLKSIZE	4096
+#ifndef roundup
+#define roundup(x, y)		((((x) + ((y) - 1)) / (y)) * (y))
+#endif
 #define NEW_ADDR	0xFFFFFFFF
 
 #ifndef FS_IOC_GETFLAGS
-- 
2.49.0



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Re: [f2fs-dev] [PATCH v2] f2fs_io: adapt w/ page_size in aligned_xalloc()

[Zhiguo Niu]

Chao Yu via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>
于2026年6月17日周三 15:36写道：
>
> When allocating memory in aligned_xalloc(), if the requested alignment
> (e.g., F2FS_DEFAULT_BLKSIZE) is smaller than the system's page size,
> aligned_alloc() will allocate memory that is not page-aligned on systems
> with 16KB or 64KB page sizes.
>
> As a result, subsequent calls to madvise(..., MADV_HUGEPAGE) will fail
> because madvise() requires the memory address and length to be page-aligned.
>
> Fix this by dynamically adjusting the alignment and rounding up the requested
> allocation size (via roundup()) to the system's page size, ensuring that
> memory is correctly page-aligned for madvise().
>
> Signed-off-by: Chao Yu <chao@kernel.org>
Reviewed-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
thanks!
> ---
>  tools/f2fs_io/f2fs_io.c | 17 +++++++++++++++++
>  tools/f2fs_io/f2fs_io.h |  3 +++
>  2 files changed, 20 insertions(+)
>
> diff --git a/tools/f2fs_io/f2fs_io.c b/tools/f2fs_io/f2fs_io.c
> index 94e61b8..9a866cc 100644
> --- a/tools/f2fs_io/f2fs_io.c
> +++ b/tools/f2fs_io/f2fs_io.c
> @@ -97,6 +97,23 @@ static void *xmalloc(size_t size)
>
>  static void *aligned_xalloc(size_t alignment, size_t size)
>  {
> +       long page_size = F2FS_DEFAULT_BLKSIZE;
> +
> +#ifdef _SC_PAGESIZE
> +       page_size = sysconf(_SC_PAGESIZE);
> +       if (page_size < 0)
> +               page_size = F2FS_DEFAULT_BLKSIZE;
> +#endif
> +
> +       /*
> +        * On systems with large page sizes (e.g., 16KB/64KB), alignment and
> +        * allocation size must be page-aligned to satisfy madvise().
> +        */
> +       if (alignment < (size_t)page_size)
> +               alignment = page_size;
> +
> +       size = roundup(size, alignment);
> +
>         void *p = aligned_alloc(alignment, size);
>
>         if (!p)
> diff --git a/tools/f2fs_io/f2fs_io.h b/tools/f2fs_io/f2fs_io.h
> index 539964f..cf1c334 100644
> --- a/tools/f2fs_io/f2fs_io.h
> +++ b/tools/f2fs_io/f2fs_io.h
> @@ -49,6 +49,9 @@ typedef u32   __be32;
>  #endif
>
>  #define F2FS_DEFAULT_BLKSIZE   4096
> +#ifndef roundup
> +#define roundup(x, y)          ((((x) + ((y) - 1)) / (y)) * (y))
> +#endif
>  #define NEW_ADDR       0xFFFFFFFF
>
>  #ifndef FS_IOC_GETFLAGS
> --
> 2.49.0
>
>
>
> _______________________________________________
> Linux-f2fs-devel mailing list
> Linux-f2fs-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel


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