On 3/7/20 3:25 PM, Andrew Morton wrote:
>
> The patch titled
> Subject: mm/gup: fixup for 9947ea2c1e608e32 "mm/gup: track FOLL_PIN pages"
> has been added to the -mm tree. Its filename is
> mm-gup-track-foll_pin-pages-fix-2.patch
>
This appears to be causing a build failure in mm/gup.c, in mmotm, as of today anyway:
commit 5d9ee416b570 ("pci: test for unexpectedly disabled bridges")
I vaguely recall reviewing an earlier version that moved put_compound_head() up higher in
gup.c, in order to avoid this. In any case, that's what this needs in order to build.
Sorry for missing it in the review.
Claudio, did you compile-test the patch? I'm not sure how this made it all the way to mmotm
without it triggering something, either, but I can't see anything obviously wrong with my
tree, which has no local changes applied.
Here's what I'm seeing, and it makes sense because put_compound_head() is actually at
line 2323:
mm/gup.c: In function ‘gup_pte_range’:
mm/gup.c:2177:4: error: implicit declaration of function ‘put_compound_head’; did you mean ‘set_compound_head’? [-Werror=implicit-function-declaration]
2177 | put_compound_head(head, 1, flags);
| ^~~~~~~~~~~~~~~~~
| set_compound_head
mm/gup.c: At top level:
mm/gup.c:2323:13: warning: conflicting types for ‘put_compound_head’
2323 | static void put_compound_head(struct page *page, int refs, unsigned int flags)
| ^~~~~~~~~~~~~~~~~
mm/gup.c:2323:13: error: static declaration of ‘put_compound_head’ follows non-static declaration
mm/gup.c:2177:4: note: previous implicit declaration of ‘put_compound_head’ was here
2177 | put_compound_head(head, 1, flags);
| ^~~~~~~~~~~~~~~~~
And here's a compile-tested (only) proposed fix:
diff --git a/mm/gup.c b/mm/gup.c
index 722fcdd32ab8..6344252f0632 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2116,6 +2116,28 @@ static inline pte_t gup_get_pte(pte_t *ptep)
}
#endif /* CONFIG_GUP_GET_PTE_LOW_HIGH */
+static void put_compound_head(struct page *page, int refs, unsigned int flags)
+{
+ if (flags & FOLL_PIN) {
+ mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_RELEASED,
+ refs);
+
+ if (hpage_pincount_available(page))
+ hpage_pincount_sub(page, refs);
+ else
+ refs *= GUP_PIN_COUNTING_BIAS;
+ }
+
+ VM_BUG_ON_PAGE(page_ref_count(page) < refs, page);
+ /*
+ * Calling put_page() for each ref is unnecessarily slow. Only the last
+ * ref needs a put_page().
+ */
+ if (refs > 1)
+ page_ref_sub(page, refs - 1);
+ put_page(page);
+}
+
static void __maybe_unused undo_dev_pagemap(int *nr, int nr_start,
unsigned int flags,
struct page **pages)
@@ -2320,28 +2342,6 @@ static int record_subpages(struct page *page, unsigned long addr,
return nr;
}
-static void put_compound_head(struct page *page, int refs, unsigned int flags)
-{
- if (flags & FOLL_PIN) {
- mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_RELEASED,
- refs);
-
- if (hpage_pincount_available(page))
- hpage_pincount_sub(page, refs);
- else
- refs *= GUP_PIN_COUNTING_BIAS;
- }
-
- VM_BUG_ON_PAGE(page_ref_count(page) < refs, page);
- /*
- * Calling put_page() for each ref is unnecessarily slow. Only the last
- * ref needs a put_page().
- */
- if (refs > 1)
- page_ref_sub(page, refs - 1);
- put_page(page);
-}
-
#ifdef CONFIG_ARCH_HAS_HUGEPD
static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
unsigned long sz)
thanks,
--
John Hubbard
NVIDIA
> This patch should soon appear at
> http://ozlabs.org/~akpm/mmots/broken-out/mm-gup-track-foll_pin-pages-fix-2.patch
> and later at
> http://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-track-foll_pin-pages-fix-2.patch
>
> Before you just go and hit "reply", please:
> a) Consider who else should be cc'ed
> b) Prefer to cc a suitable mailing list as well
> c) Ideally: find the original patch on the mailing list and do a
> reply-to-all to that, adding suitable additional cc's
>
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
>
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
>
> ------------------------------------------------------
> From: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> Subject: mm/gup: fixup for 9947ea2c1e608e32 "mm/gup: track FOLL_PIN pages"
>
> In case pin fails, we need to unpin, a simple put_page will not be enough
>
> fixup for commit 9947ea2c1e608e32 ("mm/gup: track FOLL_PIN pages")
>
> it can be simply squashed in
>
> Link: http://lkml.kernel.org/r/20200306132537.783769-2-imbrenda@xxxxxxxxxxxxx
> Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> mm/gup.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/mm/gup.c~mm-gup-track-foll_pin-pages-fix-2
> +++ a/mm/gup.c
> @@ -2065,7 +2065,7 @@ static int gup_pte_range(pmd_t pmd, unsi
> goto pte_unmap;
>
> if (unlikely(pte_val(pte) != pte_val(*ptep))) {
> - put_page(head);
> + put_compound_head(head, 1, flags);
> goto pte_unmap;
> }
>
> _
>
> Patches currently in -mm which might be from imbrenda@xxxxxxxxxxxxx are
>
> mm-gup-track-foll_pin-pages-fix-2.patch
> mm-gup-writeback-add-callbacks-for-inaccessible-pages.patch
>
