From: Uladzislau Rezki <urezki@gmail.com>
To: Baoquan He <bhe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
Matthew Wilcox <willy@infradead.org>,
Nicholas Piggin <npiggin@gmail.com>,
Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>
Subject: Re: [PATCH 3/5] mm/vmalloc: Initialize VA's list node after unlink
Date: Thu, 9 Jun 2022 15:53:26 +0200 [thread overview]
Message-ID: <CA+KHdyVGMcFhdiTwUNeFqjJCoFtXhL1T815uMD5isCTNqMSOoA@mail.gmail.com> (raw)
In-Reply-To: <YqH19tutOqChQpwM@MiWiFi-R3L-srv>
On Thu, Jun 9, 2022 at 3:30 PM Baoquan He <bhe@redhat.com> wrote:
>
> On 06/09/22 at 02:36pm, Uladzislau Rezki wrote:
> > >
> > > On 06/07/22 at 11:34am, Uladzislau Rezki (Sony) wrote:
> > > > A vmap_area can travel between different places. For example
> > > > attached/detached to/from different rb-trees. In order to
> > > > prevent fancy bugs, initialize a VA's list node after it is
> > > > removed from the list, so it pairs with VA's rb_node which
> > > > is also initialized.
> > > >
> > > > There is no functional change as a result of this patch.
> > > >
> > > > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> > > > ---
> > > > mm/vmalloc.c | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > > > index 745e89eb6ca1..82771e555273 100644
> > > > --- a/mm/vmalloc.c
> > > > +++ b/mm/vmalloc.c
> > > > @@ -978,7 +978,7 @@ __unlink_va(struct vmap_area *va, struct rb_root *root, bool augment)
> > > > else
> > > > rb_erase(&va->rb_node, root);
> > > >
> > > > - list_del(&va->list);
> > > > + list_del_init(&va->list);
> > >
> > > Don't object this change, while list_del poison members, which is also
> > > not bad?
> > >
> > It is not bad for sure. The main aim was to be align with what the
> > RB_CLEAR_NODE() does, i.e. initialize VA when it is detached
> > and be safe with list manipulation when it is detached. For example
> > whether it is empty or not: list_empty(), etc.
>
> Agree. list_del() can't make list_empty() work, and RB_CLEAR_NODE() has
> done the clearing already.
>
> Then this change looks reasonable to me, thanks.
>
> Reviewed-by: Baoquan He <bhe@redhat.com>
>
Thanks!
--
Uladzislau Rezki
next prev parent reply other threads:[~2022-06-09 13:53 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-07 9:34 [PATCH 0/5] Reduce a vmalloc internal lock contention preparation work Uladzislau Rezki (Sony)
2022-06-07 9:34 ` [PATCH 1/5] mm/vmalloc: Make link_va()/unlink_va() common to different rb_root Uladzislau Rezki (Sony)
2022-06-08 3:45 ` Baoquan He
2022-06-07 9:34 ` [PATCH 2/5] mm/vmalloc: Extend __alloc_vmap_area() with extra arguments Uladzislau Rezki (Sony)
2022-06-07 9:49 ` Christoph Hellwig
2022-06-07 13:02 ` Uladzislau Rezki
2022-06-10 8:18 ` Christoph Hellwig
2022-06-08 3:46 ` Baoquan He
2022-06-07 9:34 ` [PATCH 3/5] mm/vmalloc: Initialize VA's list node after unlink Uladzislau Rezki (Sony)
2022-06-08 3:19 ` Baoquan He
2022-06-09 12:36 ` Uladzislau Rezki
2022-06-09 13:30 ` Baoquan He
2022-06-09 13:53 ` Uladzislau Rezki [this message]
2022-06-07 9:34 ` [PATCH 4/5] mm/vmalloc: Extend __find_vmap_area() with one more argument Uladzislau Rezki (Sony)
2022-06-07 9:47 ` Christoph Hellwig
2022-06-07 13:03 ` Uladzislau Rezki
2022-06-08 3:47 ` Baoquan He
2022-06-07 9:34 ` [PATCH 5/5] lib/test_vmalloc: Switch to prandom_u32() Uladzislau Rezki (Sony)
2022-06-07 22:35 ` [PATCH 0/5] Reduce a vmalloc internal lock contention preparation work Andrew Morton
2022-06-08 10:05 ` Uladzislau Rezki
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