From: Pasha Tatashin <pasha.tatashin@soleen.com>
To: pasha.tatashin@soleen.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linux-m68k@lists.linux-m68k.org,
anshuman.khandual@arm.com, willy@infradead.org,
akpm@linux-foundation.org, william.kucharski@oracle.com,
mike.kravetz@oracle.com, vbabka@suse.cz, geert@linux-m68k.org,
schmitzmic@gmail.com, rostedt@goodmis.org, mingo@redhat.com,
hannes@cmpxchg.org, guro@fb.com, songmuchun@bytedance.com,
weixugc@google.com, gthelen@google.com
Subject: [RFC 2/8] mm/hugetlb: remove useless set_page_count()
Date: Tue, 26 Oct 2021 17:38:16 +0000 [thread overview]
Message-ID: <20211026173822.502506-3-pasha.tatashin@soleen.com> (raw)
In-Reply-To: <20211026173822.502506-1-pasha.tatashin@soleen.com>
prep_compound_gigantic_page() calls set_page_count(0, p), but it is not
needed because page_ref_freeze(p, 1) already sets refcount to 0.
Using, set_page_count() is dangerous, because it unconditionally resets
refcount from the current value to unrestrained value, and therefore
should be minimized.
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
---
mm/hugetlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 95dc7b83381f..7e3996c8b696 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1707,7 +1707,7 @@ static bool prep_compound_gigantic_page(struct page *page, unsigned int order)
pr_warn("HugeTLB page can not be used due to unexpected inflated ref count\n");
goto out_error;
}
- set_page_count(p, 0);
+ VM_BUG_ON_PAGE(page_count(p), p);
set_compound_head(p, page);
}
atomic_set(compound_mapcount_ptr(page), -1);
--
2.33.0.1079.g6e70778dc9-goog
next prev parent reply other threads:[~2021-10-26 17:38 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-26 17:38 [RFC 0/8] Hardening page _refcount Pasha Tatashin
2021-10-26 17:38 ` [RFC 1/8] mm: add overflow and underflow checks for page->_refcount Pasha Tatashin
2021-10-26 19:48 ` Matthew Wilcox
2021-10-26 21:34 ` Pasha Tatashin
2021-10-27 1:21 ` Pasha Tatashin
2021-10-27 3:04 ` Matthew Wilcox
2021-10-27 18:22 ` Pasha Tatashin
2021-10-27 7:46 ` Muchun Song
2021-10-27 18:22 ` Pasha Tatashin
2021-10-28 4:08 ` Muchun Song
2021-10-26 17:38 ` Pasha Tatashin [this message]
2021-10-26 18:44 ` [RFC 2/8] mm/hugetlb: remove useless set_page_count() Mike Kravetz
2021-10-26 18:50 ` Pasha Tatashin
2021-10-26 21:19 ` Mike Kravetz
2021-10-26 17:38 ` [RFC 3/8] mm: Avoid using set_page_count() in set_page_recounted() Pasha Tatashin
2021-10-26 17:53 ` John Hubbard
2021-10-26 18:01 ` John Hubbard
2021-10-26 18:14 ` Pasha Tatashin
2021-10-26 18:21 ` Pasha Tatashin
2021-10-27 5:12 ` John Hubbard
2021-10-27 18:27 ` Pasha Tatashin
2021-10-28 1:20 ` John Hubbard
2021-10-28 1:35 ` John Hubbard
2021-11-01 14:30 ` Pasha Tatashin
2021-11-01 19:35 ` John Hubbard
2021-11-01 14:22 ` Pasha Tatashin
2021-11-01 19:31 ` John Hubbard
2021-11-01 19:42 ` John Hubbard
2021-10-26 17:38 ` [RFC 4/8] mm: remove set_page_count() from page_frag_alloc_align Pasha Tatashin
2021-10-26 17:38 ` [RFC 5/8] mm: avoid using set_page_count() when pages are freed into allocator Pasha Tatashin
2021-10-26 17:38 ` [RFC 6/8] mm: rename init_page_count() -> page_ref_init() Pasha Tatashin
2021-10-27 6:46 ` Geert Uytterhoeven
2021-10-26 17:38 ` [RFC 7/8] mm: remove set_page_count() Pasha Tatashin
2021-10-26 17:38 ` [RFC 8/8] mm: simplify page_ref_* functions Pasha Tatashin
2021-10-26 18:23 ` [RFC 0/8] Hardening page _refcount Matthew Wilcox
2021-10-26 18:30 ` Pasha Tatashin
2021-10-26 20:13 ` Matthew Wilcox
2021-10-26 21:24 ` Pasha Tatashin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211026173822.502506-3-pasha.tatashin@soleen.com \
--to=pasha.tatashin@soleen.com \
--cc=akpm@linux-foundation.org \
--cc=anshuman.khandual@arm.com \
--cc=geert@linux-m68k.org \
--cc=gthelen@google.com \
--cc=guro@fb.com \
--cc=hannes@cmpxchg.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-m68k@lists.linux-m68k.org \
--cc=linux-mm@kvack.org \
--cc=mike.kravetz@oracle.com \
--cc=mingo@redhat.com \
--cc=rostedt@goodmis.org \
--cc=schmitzmic@gmail.com \
--cc=songmuchun@bytedance.com \
--cc=vbabka@suse.cz \
--cc=weixugc@google.com \
--cc=william.kucharski@oracle.com \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.