From: Michel Lespinasse <walken@google.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>,
akpm@linux-foundation.org, peterz@infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org
Subject: Re: [PATCH -next 00/11] lib/interval-tree: move to half closed intervals
Date: Fri, 4 Oct 2019 05:43:25 -0700 [thread overview]
Message-ID: <20191004124325.GB11046@google.com> (raw)
In-Reply-To: <20191003203250.GE32665@bombadil.infradead.org>
On Thu, Oct 03, 2019 at 01:32:50PM -0700, Matthew Wilcox wrote:
> On Thu, Oct 03, 2019 at 01:18:47PM -0700, Davidlohr Bueso wrote:
> > It has been discussed[1,2] that almost all users of interval trees would better
> > be served if the intervals were actually not [a,b], but instead [a, b). This
>
> So how does a user represent a range from ULONG_MAX to ULONG_MAX now?
>
> I think the problem is that large parts of the kernel just don't consider
> integer overflow. Because we write in C, it's natural to write:
>
> for (i = start; i < end; i++)
>
> and just assume that we never need to hit ULONG_MAX or UINT_MAX.
> If we're storing addresses, that's generally true -- most architectures
> don't allow addresses in the -PAGE_SIZE to ULONG_MAX range (or they'd
> have trouble with PTR_ERR). If you're looking at file sizes, that's
> not true on 32-bit machines, and we've definitely seen filesystem bugs
> with files nudging up on 16TB (on 32 bit with 4k page size). Or block
> driver bugs with similarly sized block devices.
>
> So, yeah, easier to use. But damning corner cases.
Yeah, I wanted to ask - is the case where pgoff == ULONG_MAX (i.e.,
last block of a file that is exactly 16TB) currently supported on
32-bit archs ?
I have no idea if I am supposed to care about this or not...
--
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
next prev parent reply other threads:[~2019-10-04 12:43 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-03 20:18 [PATCH -next 00/11] lib/interval-tree: move to half closed intervals Davidlohr Bueso
2019-10-03 20:18 ` [PATCH 01/11] mm: introduce vma_interval_tree_foreach_stab() Davidlohr Bueso
2019-10-03 20:18 ` [PATCH 02/11] lib/interval-tree: add an equivalent tree with [a,b) intervals Davidlohr Bueso
2019-10-04 11:02 ` Michel Lespinasse
2019-10-03 20:18 ` [PATCH 03/11] drm/amdgpu: convert amdgpu_vm_it to half closed intervals Davidlohr Bueso
2019-10-04 6:54 ` Koenig, Christian
2019-10-04 11:36 ` Michel Lespinasse
2019-10-04 12:39 ` Christian König
2019-10-03 20:18 ` [PATCH 04/11] drm: convert drm_mm_interval_tree " Davidlohr Bueso
2019-10-03 20:18 ` [PATCH 05/11] IB/hfi1: convert __mmu_int_rb " Davidlohr Bueso
2019-10-04 11:50 ` Michel Lespinasse
2019-10-04 19:41 ` Davidlohr Bueso
2019-10-03 20:18 ` [PATCH 06/11] IB,usnic: convert usnic_uiom_interval_tree " Davidlohr Bueso
2019-10-03 20:18 ` [PATCH 07/11] vhost: convert vhost_umem_interval_tree " Davidlohr Bueso
2019-10-04 12:10 ` Michel Lespinasse
2019-10-04 19:44 ` Davidlohr Bueso
2019-10-10 5:49 ` Jason Wang
2019-10-03 20:18 ` [PATCH 08/11] mm: convert vma_interval_tree " Davidlohr Bueso
2019-10-03 20:41 ` Matthew Wilcox
2019-10-04 12:30 ` Michel Lespinasse
2019-10-03 20:18 ` [PATCH 09/11] lib/interval-tree: convert interval_tree " Davidlohr Bueso
2019-10-03 22:50 ` kbuild test robot
2019-10-04 6:57 ` Koenig, Christian
2019-10-04 7:20 ` Koenig, Christian
2019-10-08 16:59 ` Davidlohr Bueso
2019-10-03 20:18 ` [PATCH 10/11] lib: drop interval_tree_generic.h Davidlohr Bueso
2019-10-03 20:18 ` [PATCH 11/11] x86/mm, pat: convert pat tree to generic interval tree Davidlohr Bueso
2019-10-07 15:33 ` Ingo Molnar
2019-10-21 23:24 ` Davidlohr Bueso
2019-10-03 20:32 ` [PATCH -next 00/11] lib/interval-tree: move to half closed intervals Matthew Wilcox
2019-10-03 21:10 ` Davidlohr Bueso
2019-10-04 12:43 ` Michel Lespinasse [this message]
2019-10-04 0:26 ` Jason Gunthorpe
2019-10-04 2:48 ` Davidlohr Bueso
2019-10-04 13:15 ` Michel Lespinasse
2019-10-04 16:03 ` Matthew Wilcox
2019-10-04 19:35 ` Davidlohr Bueso
2019-10-04 17:45 ` Jason Gunthorpe
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