From: Matthew Wilcox <willy@infradead.org>
To: David Laight <david.laight.linux@gmail.com>
Cc: Lance Yang <ioworker0@gmail.com>,
baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com,
akpm@linux-foundation.org, axelrasmussen@google.com,
chandna.sahil@gmail.com, chengming.zhou@linux.dev,
david@kernel.org, david@redhat.com, hannes@cmpxchg.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
lorenzo.stoakes@oracle.com, mhocko@suse.com, nphamcs@gmail.com,
rppt@kernel.org, shakeel.butt@linux.dev, surenb@google.com,
vbabka@suse.cz, weixugc@google.com, yosry.ahmed@linux.dev,
yuanchu@google.com, zhengqi.arch@bytedance.com,
Lance Yang <lance.yang@linux.dev>
Subject: Re: [PATCH v4 1/3] mm: pagewalk: simplify hugepage boundary
Date: Wed, 24 Dec 2025 18:06:48 +0000 [thread overview]
Message-ID: <aUwruMji4MCNaOPi@casper.infradead.org> (raw)
In-Reply-To: <20251224140829.2ec7bbae@pumpkin>
On Wed, Dec 24, 2025 at 02:08:29PM +0000, David Laight wrote:
> > > > +++ b/mm/pagewalk.c
> > > > @@ -312,8 +312,7 @@ static int walk_pgd_range(unsigned long addr, unsigned long end,
> > > > static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
> > > > unsigned long end)
> > > > {
> > > > - unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
> > > > - return boundary < end ? boundary : end;
> > > > + return min(ALIGN(addr, huge_page_size(h)), end);
> > > > }
> > >
> > > Please drop this patch from the mm-new branch, as it causes
> > > 'run_vmtests.sh' to hang. Specifically, it leads to the system hanging
> > > when executing hugepage-vmemmap test, because the program falls into an
> > > infinite loop in walk_hugetlb_range() and cannot break out.
> >
> > Good catch! The problem is that ALIGN() returns addr itself when already
> > aligned, causing the infinite loop ...
>
> Using ALIGN(addr + 1, huge_page_size(h)) would work.
> Although it could be (addr + 1) & ~huge_page_mask(h) which is probably
> the easiest to understand.
> Some of the 'helper' macros don't really make the code easier to read.
> (And that includes a lot of uses of min().)
Or we could go back to my original suggestion.
https://lore.kernel.org/linux-mm/aRyOWrARRlUCeEz6@casper.infradead.org/
which was in v2:
https://lore.kernel.org/linux-mm/f802959f58865371ba1b10081bced98e3784c5e4.1763796152.git.chandna.sahil@gmail.com/
next prev parent reply other threads:[~2025-12-24 18:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-28 7:01 [PATCH v4 0/3] mm: Coccinelle-driven cleanups across memory management code Sahil Chandna
2025-11-28 7:01 ` [PATCH v4 1/3] mm: pagewalk: simplify hugepage boundary calculation Sahil Chandna
2025-12-24 7:50 ` Baolin Wang
2025-12-24 9:23 ` [PATCH v4 1/3] mm: pagewalk: simplify hugepage boundary Lance Yang
2025-12-24 12:46 ` Sahil Chandna
2025-12-24 14:08 ` David Laight
2025-12-24 18:06 ` Matthew Wilcox [this message]
2025-12-25 9:32 ` David Hildenbrand (Red Hat)
2025-12-25 10:01 ` David Laight
2025-11-28 7:01 ` [PATCH v4 2/3] mm/vmscan: use %pe to print error pointers Sahil Chandna
2025-11-28 7:01 ` [PATCH v4 3/3] mm/zswap: " Sahil Chandna
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