From: Leon Romanovsky <leon@kernel.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: "Margolin, Michael" <mrgolin@amazon.com>,
linux-rdma@vger.kernel.org, sleybo@amazon.com, matua@amazon.com,
gal.pressman@linux.dev, Firas Jahjah <firasj@amazon.com>,
Yonatan Nachum <ynachum@amazon.com>
Subject: Re: [PATCH for-next] RDMA/core: Fix best page size finding when it can cross SG entries
Date: Thu, 13 Feb 2025 19:55:17 +0200 [thread overview]
Message-ID: <20250213175517.GP17863@unreal> (raw)
In-Reply-To: <20250213174043.GG3754072@nvidia.com>
On Thu, Feb 13, 2025 at 01:40:43PM -0400, Jason Gunthorpe wrote:
> On Thu, Feb 13, 2025 at 07:35:10PM +0200, Leon Romanovsky wrote:
>
> > Initially curr_base is 0xFF.....FF and curr_len is 0.
>
> curr base can't be so unaligned can it?
It is only for first iteration where it is compared with
sg_dma_address(), immediately after that it is overwritten.
>
> > So if this "if ..." is skipped (not possible but static checkers don't know),
> > we will advance curr_len and curr_base + curr_len will overflow.
> >
> > I don't want to take original patch.
>
> Subtracting is no better, it will just randomly fail for low dma addrs
> instead of high.
Aren't sg_dma_address placed in increasing order?
If not, whole if loop is not correct.
If yes, we won't see any failures.
>
> You need to call check_add_overflow()
>
> Jason
next prev parent reply other threads:[~2025-02-13 17:55 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-09 14:26 [PATCH for-next] RDMA/core: Fix best page size finding when it can cross SG entries Michael Margolin
2025-02-13 12:51 ` Leon Romanovsky
2025-02-13 14:04 ` Jason Gunthorpe
2025-02-13 14:30 ` Margolin, Michael
2025-02-13 14:42 ` Jason Gunthorpe
2025-02-13 17:25 ` Margolin, Michael
2025-02-13 17:35 ` Leon Romanovsky
2025-02-13 17:40 ` Jason Gunthorpe
2025-02-13 17:55 ` Leon Romanovsky [this message]
2025-02-13 18:12 ` Jason Gunthorpe
2025-02-14 5:55 ` Leon Romanovsky
2025-02-14 15:33 ` Jason Gunthorpe
2025-02-16 8:07 ` Leon Romanovsky
2025-02-17 8:40 ` Margolin, Michael
2025-02-13 12:53 ` Leon Romanovsky
2025-02-14 6:57 ` Leon Romanovsky
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