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mm/gup: further simplify __gup_device_huge() 

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2023396

This patch is a backport of the following upstream commit:
commit 20b7fee738d65e50ca00e325ae27ee3efaa819f6
Author: John Hubbard <jhubbard@nvidia.com>
Date:   Fri Nov 5 13:37:16 2021 -0700

    mm/gup: further simplify __gup_device_huge()

    Commit 6401c4eb57f9 ("mm: gup: fix potential pgmap refcnt leak in
    __gup_device_huge()") simplified the return paths, but didn't go quite
    far enough, as discussed in [1].

    Remove the "ret" variable entirely, because there is enough information
    already available to provide the return value.

    [1] https://lore.kernel.org/r/CAHk-=wgQTRX=5SkCmS+zfmpqubGHGJvXX_HgnPG8JSpHKHBMeg@mail.gmail.com

    Link: https://lkml.kernel.org/r/20210904004224.86391-1-jhubbard@nvidia.com
    Signed-off-by: John Hubbard <jhubbard@nvidia.com>
    Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
    Reviewed-by: Jan Kara <jack@suse.cz>
    Cc: Miaohe Lin <linmiaohe@huawei.com>
    Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
    Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Rafael Aquini <aquini@redhat.com>
This commit is contained in:
Rafael Aquini 2021-11-29 11:39:05 -05:00
parent 5505b1183b
commit 090e6ac2d2
1 changed files with 1 additions and 4 deletions
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5
mm/gup.c
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@ -2228,7 +2228,6 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
{
int nr_start = *nr;
struct dev_pagemap *pgmap = NULL;
int ret = 1;
do {
struct page *page = pfn_to_page(pfn);
@ -2236,14 +2235,12 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
pgmap = get_dev_pagemap(pfn, pgmap);
if (unlikely(!pgmap)) {
undo_dev_pagemap(nr, nr_start, flags, pages);
ret = 0;
break;
}
SetPageReferenced(page);
pages[*nr] = page;
if (unlikely(!try_grab_page(page, flags))) {
undo_dev_pagemap(nr, nr_start, flags, pages);
ret = 0;
break;
}
(*nr)++;
@ -2251,7 +2248,7 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
} while (addr += PAGE_SIZE, addr != end);
put_dev_pagemap(pgmap);
return ret;
return addr == end;
}
static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,