From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] mm/mmap: Regression fix for unmapped_area{_topdown}
Date: Fri, 14 Apr 2023 13:29:19 -0400 [thread overview]
Message-ID: <20230414172919.ynxybbocc4o4tbtd@revolver> (raw)
In-Reply-To: <20230414172610.f35pngvz6cilxsdq@revolver>
* Liam R. Howlett <Liam.Howlett@Oracle.com> [230414 13:26]:
> * Edgecombe, Rick P <rick.p.edgecombe@intel.com> [230414 12:27]:
> > On Fri, 2023-04-14 at 10:57 -0400, Liam R. Howlett wrote:<br>
> > > + tmp = mas_next(&mas, ULONG_MAX);
> > > + if (tmp && (tmp->vm_flags & VM_GROWSDOWN)) {
> >
> > Why also check VM_GROWSDOWN here (and VM_GROWSUP below)?
> > vm_start/end_gap() already have checks inside.
>
> An artifact of a plan that was later abandoned.
>
> >
> > > + if (vm_start_gap(tmp) < gap + length - 1) {
> > > + low_limit = tmp->vm_end;
> > > + mas_reset(&mas);
> > > + goto retry;
> > > + }
> > > + } else {
> > > + tmp = mas_prev(&mas, 0);
> > > + if (tmp && (tmp->vm_flags & VM_GROWSUP) &&
> > > + vm_end_gap(tmp) > gap) {
> > > + low_limit = vm_end_gap(tmp);
> > > + mas_reset(&mas);
> > > + goto retry;
> > > + }
> > > + }
> > > +
> >
> > Could it be like this?
>
> Yes, I'll make this change. Thanks for the suggestion.
Wait, I like how it is.
In my version, if there is a stack that is VM_GROWSDOWN there, but does
not intercept the gap, then I won't check the prev.. in yours, we will
never avoid checking prev.
>
> >
> > tmp = mas_next(&mas, ULONG_MAX);
> > if (tmp && vm_start_gap(tmp) < gap + length - 1) {
> > low_limit = tmp->vm_end;
> > mas_reset(&mas);
> > goto retry;
> > }
> > } else {
> > tmp = mas_prev(&mas, 0);
> > if (tmp && vm_end_gap(tmp) > gap) {
> > low_limit = vm_end_gap(tmp);
> > mas_reset(&mas);
> > goto retry;
> > }
> > }
> >
next prev parent reply other threads:[~2023-04-14 17:29 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-14 14:57 [PATCH 1/3] maple_tree: Make maple state reusable after mas_empty_area_rev() Liam R. Howlett
2023-04-14 14:57 ` [PATCH 2/3] maple_tree: Fix mas_empty_area() search Liam R. Howlett
2023-04-14 14:57 ` [PATCH 3/3] mm/mmap: Regression fix for unmapped_area{_topdown} Liam R. Howlett
2023-04-14 16:27 ` Edgecombe, Rick P
2023-04-14 17:26 ` Liam R. Howlett
2023-04-14 17:29 ` Liam R. Howlett [this message]
2023-04-14 17:53 ` Edgecombe, Rick P
2023-04-14 18:07 ` Liam R. Howlett
2023-04-14 18:21 ` Edgecombe, Rick P
2023-04-14 18:59 ` [PATCH v2] " Liam R. Howlett
2023-04-14 19:09 ` Andrew Morton
2023-04-29 14:32 ` Tad
2023-04-30 22:41 ` Michael Keyes
2023-05-02 14:08 ` Liam R. Howlett
2023-05-02 14:09 ` Liam R. Howlett
2023-05-15 8:57 ` Juhyung Park
2023-05-15 14:36 ` Liam R. Howlett
2023-04-19 9:02 ` [PATCH 1/3] maple_tree: Make maple state reusable after mas_empty_area_rev() Peng Zhang
2023-04-19 22:54 ` Liam R. Howlett
2023-04-20 4:21 ` Peng Zhang
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