[GIT PULL] Modules changes for v6.7-rc1

[GIT PULL] Modules changes for v6.7-rc1

[Luis Chamberlain]

The following changes since commit 7d461b291e65938f15f56fe58da2303b07578a76:

  Merge tag 'drm-next-2023-10-31-1' of git://anongit.freedesktop.org/drm/drm (2023-11-01 06:28:35 -1000)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux.git/ tags/modules-6.7-rc1

for you to fetch changes up to ea0b0bcef4917a2640ecc100c768b8e785784834:

  module: Annotate struct module_notes_attrs with __counted_by (2023-11-01 13:07:32 -0700)

----------------------------------------------------------------
Modules changes for v6.7-rc1

The only thing worth highligthing is that gzip moves to use vmalloc() instead of
kmalloc just as we had a fix for this for zstd on v6.6-rc1. The rest is regular
house keeping, keeping things neat, tidy, and boring.

Oh and this has been on linux-next for over a month.

----------------------------------------------------------------
Andrea Righi (1):
      module/decompress: use vmalloc() for gzip decompression workspace

Kees Cook (2):
      module: Clarify documentation of module_param_call()
      module: Annotate struct module_notes_attrs with __counted_by

Luis Chamberlain (1):
      MAINTAINERS: add include/linux/module*.h to modules

Tiezhu Yang (2):
      module: Make is_mapping_symbol() return bool
      module: Make is_valid_name() return bool

Zhu Mao (1):
      module: Fix comment typo

 MAINTAINERS                   | 2 +-
 include/linux/module_symbol.h | 2 +-
 include/linux/moduleparam.h   | 6 +++++-
 kernel/module/decompress.c    | 4 ++--
 kernel/module/stats.c         | 2 +-
 kernel/module/sysfs.c         | 2 +-
 scripts/mod/modpost.c         | 4 ++--
 7 files changed, 13 insertions(+), 9 deletions(-)

Re: [GIT PULL] Modules changes for v6.7-rc1

[Linus Torvalds]

On Wed, 1 Nov 2023 at 10:13, Luis Chamberlain <mcgrof@kernel.org> wrote:
>
> The only thing worth highligthing is that gzip moves to use vmalloc() instead of
> kmalloc just as we had a fix for this for zstd on v6.6-rc1.

Actually, that's almost certainly entirely the wrong thing to do.

Unless you *know* that the allocation is large, you shouldn't use
vmalloc(). And since kmalloc() has worked fine, you most definitely
don't know that.

So we have 'kvmalloc()' *exactly* for this reason, which is a "use
kmalloc, unless that is too small, then use vmalloc".

kmalloc() isn't just about "use physically contiguous allocations".
It's also more memory-efficient, and a *lot* faster than vmalloc(),
which has to play VM tricks.

So this "just switch to vmalloc()" is entirely wrong.

              Linus

Re: [GIT PULL] Modules changes for v6.7-rc1

[Linus Torvalds]

[-- Attachment #1: Type: text/plain, Size: 371 bytes --]

On Wed, 1 Nov 2023 at 21:02, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> kmalloc() isn't just about "use physically contiguous allocations".
> It's also more memory-efficient, and a *lot* faster than vmalloc(),
> which has to play VM tricks.

I've pulled this, but I think you should do something like the
attached (UNTESTED!) patch.

                Linus

[-- Attachment #2: patch.diff --]
[-- Type: text/x-patch, Size: 1261 bytes --]

 kernel/module/decompress.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c
index 4156d59be440..474e68f0f063 100644
--- a/kernel/module/decompress.c
+++ b/kernel/module/decompress.c
@@ -100,7 +100,7 @@ static ssize_t module_gzip_decompress(struct load_info *info,
 	s.next_in = buf + gzip_hdr_len;
 	s.avail_in = size - gzip_hdr_len;
 
-	s.workspace = vmalloc(zlib_inflate_workspacesize());
+	s.workspace = kvmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
 	if (!s.workspace)
 		return -ENOMEM;
 
@@ -138,7 +138,7 @@ static ssize_t module_gzip_decompress(struct load_info *info,
 out_inflate_end:
 	zlib_inflateEnd(&s);
 out:
-	vfree(s.workspace);
+	kvfree(s.workspace);
 	return retval;
 }
 #elif defined(CONFIG_MODULE_COMPRESS_XZ)
@@ -241,7 +241,7 @@ static ssize_t module_zstd_decompress(struct load_info *info,
 	}
 
 	wksp_size = zstd_dstream_workspace_bound(header.windowSize);
-	wksp = vmalloc(wksp_size);
+	wksp = kvmalloc(wksp_size, GFP_KERNEL);
 	if (!wksp) {
 		retval = -ENOMEM;
 		goto out;
@@ -284,7 +284,7 @@ static ssize_t module_zstd_decompress(struct load_info *info,
 	retval = new_size;
 
  out:
-	vfree(wksp);
+	kvfree(wksp);
 	return retval;
 }
 #else

Re: [GIT PULL] Modules changes for v6.7-rc1

[Andrea Righi]

On Wed, Nov 01, 2023 at 09:02:51PM -1000, Linus Torvalds wrote:
> On Wed, 1 Nov 2023 at 10:13, Luis Chamberlain <mcgrof@kernel.org> wrote:
> >
> > The only thing worth highligthing is that gzip moves to use vmalloc() instead of
> > kmalloc just as we had a fix for this for zstd on v6.6-rc1.
> 
> Actually, that's almost certainly entirely the wrong thing to do.
> 
> Unless you *know* that the allocation is large, you shouldn't use
> vmalloc(). And since kmalloc() has worked fine, you most definitely
> don't know that.
> 
> So we have 'kvmalloc()' *exactly* for this reason, which is a "use
> kmalloc, unless that is too small, then use vmalloc".
> 
> kmalloc() isn't just about "use physically contiguous allocations".
> It's also more memory-efficient, and a *lot* faster than vmalloc(),
> which has to play VM tricks.
> 
> So this "just switch to vmalloc()" is entirely wrong.
> 
>               Linus

I proposed that change mostlfy for consistency with the zstd case, but I
haven't experience any issue with gzip compressed modules (that seem to
require less memory, even with larger modules).

So, yes, it probably makes sense to drop this change for now and I can
send another patch to switch to kvmalloc() for all the decompress cases.

Thanks,
-Andrea

Re: [GIT PULL] Modules changes for v6.7-rc1

[pr-tracker-bot]

The pull request you sent on Wed, 1 Nov 2023 13:13:03 -0700:

> git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux.git/ tags/modules-6.7-rc1

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/21e80f3841c01aeaf32d7aee7bbc87b3db1aa0c6

Thank you!

-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/prtracker.html

Re: [GIT PULL] Modules changes for v6.7-rc1

[Andrea Righi]

On Wed, Nov 01, 2023 at 09:21:09PM -1000, Linus Torvalds wrote:
> On Wed, 1 Nov 2023 at 21:02, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > kmalloc() isn't just about "use physically contiguous allocations".
> > It's also more memory-efficient, and a *lot* faster than vmalloc(),
> > which has to play VM tricks.
> 
> I've pulled this, but I think you should do something like the
> attached (UNTESTED!) patch.
> 
>                 Linus

Looks good to me, I'll give it a try ASAP.

-Andrea


>  kernel/module/decompress.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c
> index 4156d59be440..474e68f0f063 100644
> --- a/kernel/module/decompress.c
> +++ b/kernel/module/decompress.c
> @@ -100,7 +100,7 @@ static ssize_t module_gzip_decompress(struct load_info *info,
>  	s.next_in = buf + gzip_hdr_len;
>  	s.avail_in = size - gzip_hdr_len;
>  
> -	s.workspace = vmalloc(zlib_inflate_workspacesize());
> +	s.workspace = kvmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
>  	if (!s.workspace)
>  		return -ENOMEM;
>  
> @@ -138,7 +138,7 @@ static ssize_t module_gzip_decompress(struct load_info *info,
>  out_inflate_end:
>  	zlib_inflateEnd(&s);
>  out:
> -	vfree(s.workspace);
> +	kvfree(s.workspace);
>  	return retval;
>  }
>  #elif defined(CONFIG_MODULE_COMPRESS_XZ)
> @@ -241,7 +241,7 @@ static ssize_t module_zstd_decompress(struct load_info *info,
>  	}
>  
>  	wksp_size = zstd_dstream_workspace_bound(header.windowSize);
> -	wksp = vmalloc(wksp_size);
> +	wksp = kvmalloc(wksp_size, GFP_KERNEL);
>  	if (!wksp) {
>  		retval = -ENOMEM;
>  		goto out;
> @@ -284,7 +284,7 @@ static ssize_t module_zstd_decompress(struct load_info *info,
>  	retval = new_size;
>  
>   out:
> -	vfree(wksp);
> +	kvfree(wksp);
>  	return retval;
>  }
>  #else

Re: [GIT PULL] Modules changes for v6.7-rc1

[Andrea Righi]

On Thu, Nov 02, 2023 at 08:29:17AM +0100, Andrea Righi wrote:
> On Wed, Nov 01, 2023 at 09:21:09PM -1000, Linus Torvalds wrote:
> > On Wed, 1 Nov 2023 at 21:02, Linus Torvalds
> > <torvalds@linux-foundation.org> wrote:
> > >
> > > kmalloc() isn't just about "use physically contiguous allocations".
> > > It's also more memory-efficient, and a *lot* faster than vmalloc(),
> > > which has to play VM tricks.
> > 
> > I've pulled this, but I think you should do something like the
> > attached (UNTESTED!) patch.
> > 
> >                 Linus
> 
> Looks good to me, I'll give it a try ASAP.
> 
> -Andrea

Just tested this both with zstd and gzip module compression, all good.

You can add my:

Tested-by: Andrea Righi <andrea.righi@canonical.com>

Or if you need a proper paperwork:

--

From: Andrea Righi <andrea.righi@canonical.com>
Subject: [PATCH] module/decompress: use kvmalloc() consistently

We consistently switched from kmalloc() to vmalloc() in module
decompression to prevent potential memory allocation failures with large
modules, however vmalloc() is not as memory-efficient and fast as
kmalloc().

Since we don't know in general the size of the workspace required by the
decompression algorithm, it is more reasonable to use kvmalloc()
consistently, also considering that we don't have special memory
requirements here.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
---
 kernel/module/decompress.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c
index 4156d59be440..474e68f0f063 100644
--- a/kernel/module/decompress.c
+++ b/kernel/module/decompress.c
@@ -100,7 +100,7 @@ static ssize_t module_gzip_decompress(struct load_info *info,
 	s.next_in = buf + gzip_hdr_len;
 	s.avail_in = size - gzip_hdr_len;
 
-	s.workspace = vmalloc(zlib_inflate_workspacesize());
+	s.workspace = kvmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
 	if (!s.workspace)
 		return -ENOMEM;
 
@@ -138,7 +138,7 @@ static ssize_t module_gzip_decompress(struct load_info *info,
 out_inflate_end:
 	zlib_inflateEnd(&s);
 out:
-	vfree(s.workspace);
+	kvfree(s.workspace);
 	return retval;
 }
 #elif defined(CONFIG_MODULE_COMPRESS_XZ)
@@ -241,7 +241,7 @@ static ssize_t module_zstd_decompress(struct load_info *info,
 	}
 
 	wksp_size = zstd_dstream_workspace_bound(header.windowSize);
-	wksp = vmalloc(wksp_size);
+	wksp = kvmalloc(wksp_size, GFP_KERNEL);
 	if (!wksp) {
 		retval = -ENOMEM;
 		goto out;
@@ -284,7 +284,7 @@ static ssize_t module_zstd_decompress(struct load_info *info,
 	retval = new_size;
 
  out:
-	vfree(wksp);
+	kvfree(wksp);
 	return retval;
 }
 #else
-- 
2.40.1