Thread (66 messages) 66 messages, 8 authors, 2025-09-18

Re: [PATCH 08/10] mm: update fork mm->flags initialisation to use bitmap

From: Lorenzo Stoakes <hidden>
Date: 2025-08-26 16:27:09
Also in: linux-fsdevel, linux-mm, linux-perf-users, linux-s390, lkml, sparclinux

On Tue, Aug 26, 2025 at 05:53:36PM +0200, David Hildenbrand wrote:
quoted
OK right I see, in both cases BIT(32) is going to cause a warning on 32-bit.

I was wrong in thinking (u64)(1UL << 32) would get fixed up because of the
outer cast I guess.

This was the mistake here, so fine, we could do it this way.

I guess I'll have to respin the series at this point.
Let me think again: assuming someone would mess up the BIT() thing and
convert back to 1 << NR, your variant would catch it on 32bit I guess.
Yeah and it should also catch the BIT() case albeit via warning :P
So given I was primarily confused by the "u64" when talking about 32it, no
need for a full resend of this series just to clean this up.
Yeah this isn't _terrible_ I don't think, although I was labouring under a
misapprehension (understandable - hopefully :) in the way the casting would
work, but of course you're right the ub would happen _prior_ to the u64 cast.

Anyway I think net we're getting the same result, and the comment makes clear
the intent, so I think yeah sort of fine as-is.

But I take your point absolutely :)

Cheers, Lorenzo
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