From: Ira Weiny <[email protected]>
To: "Fabio M. De Francesco" <[email protected]>
Cc: Benjamin LaHaise <[email protected]>,
Alexander Viro <[email protected]>,
Eric Biederman <[email protected]>,
Kees Cook <[email protected]>,
Dan Williams <[email protected]>,
"Matthew Wilcox" <[email protected]>, Jan Kara <[email protected]>,
Jeff Layton <[email protected]>,
Chuck Lever <[email protected]>,
Jens Axboe <[email protected]>,
Pavel Begunkov <[email protected]>,
Thomas Gleixner <[email protected]>,
Paul Walmsley <[email protected]>,
"Palmer Dabbelt" <[email protected]>,
Albert Ou <[email protected]>,
"Nathan Chancellor" <[email protected]>,
Nick Desaulniers <[email protected]>,
Tom Rix <[email protected]>, <[email protected]>,
<[email protected]>, <[email protected]>,
<[email protected]>, <[email protected]>,
<[email protected]>, <[email protected]>,
<[email protected]>
Subject: Re: [PATCH] fs: Replace kmap{,_atomic}() with kmap_local_page()
Date: Fri, 8 Jul 2022 13:18:35 -0700 [thread overview]
Message-ID: <YsiQptk19txHrG4c@iweiny-desk3> (raw)
In-Reply-To: <[email protected]>
On Thu, Jun 30, 2022 at 06:35:27PM +0200, Fabio M. De Francesco wrote:
> The use of kmap() and kmap_atomic() are being deprecated in favor of
> kmap_local_page().
>
> With kmap_local_page(), the mappings are per thread, CPU local and not
> globally visible. Furthermore, the mappings can be acquired from any
> context (including interrupts).
>
> Therefore, use kmap_local_page() in exec.c because these mappings are per
> thread, CPU local, and not globally visible.
>
> Tested with xfstests on a QEMU + KVM 32-bits VM booting a kernel with
> HIGHMEM64GB enabled.
>
> Suggested-by: Ira Weiny <[email protected]>
This looks good but there is a kmap_atomic() in this file which I _think_ can
be converted as well. But that is good as a separate patch.
Reviewed-by: Ira Weiny <[email protected]>
> Signed-off-by: Fabio M. De Francesco <[email protected]>
> ---
> fs/exec.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index 0989fb8472a1..4a2129c0d422 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -583,11 +583,11 @@ static int copy_strings(int argc, struct user_arg_ptr argv,
>
> if (kmapped_page) {
> flush_dcache_page(kmapped_page);
> - kunmap(kmapped_page);
> + kunmap_local(kaddr);
> put_arg_page(kmapped_page);
> }
> kmapped_page = page;
> - kaddr = kmap(kmapped_page);
> + kaddr = kmap_local_page(kmapped_page);
> kpos = pos & PAGE_MASK;
> flush_arg_page(bprm, kpos, kmapped_page);
> }
> @@ -601,7 +601,7 @@ static int copy_strings(int argc, struct user_arg_ptr argv,
> out:
> if (kmapped_page) {
> flush_dcache_page(kmapped_page);
> - kunmap(kmapped_page);
> + kunmap_local(kaddr);
> put_arg_page(kmapped_page);
> }
> return ret;
> @@ -883,11 +883,11 @@ int transfer_args_to_stack(struct linux_binprm *bprm,
>
> for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
> unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
> - char *src = kmap(bprm->page[index]) + offset;
> + char *src = kmap_local_page(bprm->page[index]) + offset;
> sp -= PAGE_SIZE - offset;
> if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
> ret = -EFAULT;
> - kunmap(bprm->page[index]);
> + kunmap_local(src);
> if (ret)
> goto out;
> }
> @@ -1680,13 +1680,13 @@ int remove_arg_zero(struct linux_binprm *bprm)
> ret = -EFAULT;
> goto out;
> }
> - kaddr = kmap_atomic(page);
> + kaddr = kmap_local_page(page);
>
> for (; offset < PAGE_SIZE && kaddr[offset];
> offset++, bprm->p++)
> ;
>
> - kunmap_atomic(kaddr);
> + kunmap_local(kaddr);
> put_arg_page(page);
> } while (offset == PAGE_SIZE);
>
> --
> 2.36.1
>
next prev parent reply other threads:[~2022-07-08 20:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-30 16:35 [PATCH] fs: Replace kmap{,_atomic}() with kmap_local_page() Fabio M. De Francesco
2022-06-30 17:38 ` Eric W. Biederman
2022-07-01 10:10 ` Fabio M. De Francesco
2022-07-08 20:18 ` Ira Weiny [this message]
2022-07-09 18:30 ` Fabio M. De Francesco
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