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    SubjectRe: [PATCH v2] kexec: Replace kmap() with kmap_local_page()
    On Fri, Jul 08, 2022 at 01:15:50AM +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 kexec_core.c because these mappings are
    > per thread, CPU local, and not globally visible.
    >
    > Tested on a QEMU + KVM 32-bits VM booting a kernel with HIGHMEM64GB
    > enabled.
    >
    > Suggested-by: Ira Weiny <ira.weiny@intel.com>

    Reviewed-by: Ira Weiny <ira.weiny@intel.com>

    > Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
    > ---
    >
    > v1->v2: A sentence of the commit message contained an error due to a
    > mistake in copy-pasting from a previous patch. Replace "aio.c" with
    > "kexec_core.c".
    >
    > kernel/kexec_core.c | 8 ++++----
    > 1 file changed, 4 insertions(+), 4 deletions(-)
    >
    > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
    > index 4d34c78334ce..6f98274765d4 100644
    > --- a/kernel/kexec_core.c
    > +++ b/kernel/kexec_core.c
    > @@ -814,7 +814,7 @@ static int kimage_load_normal_segment(struct kimage *image,
    > if (result < 0)
    > goto out;
    >
    > - ptr = kmap(page);
    > + ptr = kmap_local_page(page);
    > /* Start with a clear page */
    > clear_page(ptr);
    > ptr += maddr & ~PAGE_MASK;
    > @@ -827,7 +827,7 @@ static int kimage_load_normal_segment(struct kimage *image,
    > memcpy(ptr, kbuf, uchunk);
    > else
    > result = copy_from_user(ptr, buf, uchunk);
    > - kunmap(page);
    > + kunmap_local(ptr);
    > if (result) {
    > result = -EFAULT;
    > goto out;
    > @@ -878,7 +878,7 @@ static int kimage_load_crash_segment(struct kimage *image,
    > goto out;
    > }
    > arch_kexec_post_alloc_pages(page_address(page), 1, 0);
    > - ptr = kmap(page);
    > + ptr = kmap_local_page(page);
    > ptr += maddr & ~PAGE_MASK;
    > mchunk = min_t(size_t, mbytes,
    > PAGE_SIZE - (maddr & ~PAGE_MASK));
    > @@ -894,7 +894,7 @@ static int kimage_load_crash_segment(struct kimage *image,
    > else
    > result = copy_from_user(ptr, buf, uchunk);
    > kexec_flush_icache_page(page);
    > - kunmap(page);
    > + kunmap_local(ptr);
    > arch_kexec_pre_free_pages(page_address(page), 1);
    > if (result) {
    > result = -EFAULT;
    > --
    > 2.36.1
    >

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