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From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Kirill Shutemov <kirill@shutemov.name>,
	Wei Zhang <wzam@amazon.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Matthew Wilcox <willy@infradead.org>,
	Miaohe Lin <linmiaohe@huawei.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	peterx@redhat.com, Gal Pressman <galpress@amazon.com>,
	Jan Kara <jack@suse.cz>, Jann Horn <jannh@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kirill Tkhai <ktkhai@virtuozzo.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	David Gibson <david@gibson.dropbear.id.au>,
	Christoph Hellwig <hch@lst.de>
Subject: [PATCH v2 2/4] hugetlg: Break earlier in add_reservation_in_range() when we can
Date: Thu,  4 Feb 2021 09:50:31 -0500	[thread overview]
Message-ID: <20210204145033.136755-3-peterx@redhat.com> (raw)
In-Reply-To: <20210204145033.136755-1-peterx@redhat.com>

All the regions maintained in hugetlb reserved map is inclusive on "from" but
exclusive on "to".  We can break earlier even if rg->from==t because it already
means no possible intersection.

This does not need a Fixes in all cases because when it happens (rg->from==t)
we'll not break out of the loop while we should, however the next thing we'd do
is still add the last file_region we'd need and quit the loop in the next
round.  So this change is not a bugfix (since the old code should still run
okay iiuc), but we'd better still touch it up to make it logically sane.

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 mm/hugetlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index d2859c2aecc9..9e6ea96bf33b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -377,7 +377,7 @@ static long add_reservation_in_range(struct resv_map *resv, long f, long t,
 		/* When we find a region that starts beyond our range, we've
 		 * finished.
 		 */
-		if (rg->from > t)
+		if (rg->from >= t)
 			break;
 
 		/* Add an entry for last_accounted_offset -> rg->from, and
-- 
2.26.2


  parent reply	other threads:[~2021-02-04 14:53 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-04 14:50 [PATCH v2 0/4] mm/hugetlb: Early cow on fork, and a few cleanups Peter Xu
2021-02-04 14:50 ` [PATCH v2 1/4] hugetlb: Dedup the code to add a new file_region Peter Xu
2021-02-04 14:50 ` Peter Xu [this message]
2021-02-04 14:50 ` [PATCH v2 3/4] mm: Introduce page_needs_cow_for_dma() for deciding whether cow Peter Xu
2021-02-04 17:54   ` Linus Torvalds
2021-02-04 19:25     ` Peter Xu
2021-02-04 23:20   ` Jason Gunthorpe
2021-02-05  0:50     ` Peter Xu
2021-02-04 14:50 ` [PATCH v2 4/4] hugetlb: Do early cow when page pinned on src mm Peter Xu
2021-02-04 23:25   ` Mike Kravetz
2021-02-05  1:43     ` Peter Xu
2021-02-05  5:11       ` Mike Kravetz
2021-02-05 16:05         ` Peter Xu
     [not found]   ` <329ADC08-552E-423B-9230-99643B81C14A@amazon.com>
2021-02-05 15:51     ` Peter Xu
2021-02-07  9:09       ` Gal Pressman
2021-02-07 15:31         ` Peter Xu
2021-02-04 20:20 ` [PATCH v2 5/4] mm: Use is_cow_mapping() across tree where proper Peter Xu
2021-02-04 20:26   ` Linus Torvalds

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