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b=eem74xGmmfxX4i5JGj5geIWcHbuRewGhh7jtDenQX1rUPWDua13ZDJoWcbiBDD6xv RqDLgzNIa3BbyJlCevTg8MNcziZWAbPAG7qqrRUvwgaXnhXrFcn+AzZxoq6a92f/5g uu0HuXuNHMYFgYdinigoKyGTDpiIZd7gCDmOr330AFuevEFo84RBz6zmUtC6J4UzZj 2dgDt0mxAPahvRLYoJwwmFtFHQLbemX2BLnJEZcKRx5k049uI1QCAPV0r48fFZbzMq RRcM/Pwx41eRaDNfkvMjOm7ky+QtZng3gVmecZLGxWtgSQs3u1PFrgpBWbL5dW1cHL Qfo3l3WHevXLQ== Date: Sun, 9 Aug 2026 17:03:37 +0300 From: Mike Rapoport To: Longlong Xia Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Longlong Xia Subject: Re: [PATCH 1/1] mm/mm_init: compute hash mask with unsigned arithmetic Message-ID: References: <20260809123119.3811851-1-xialonglong2025@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260809123119.3811851-1-xialonglong2025@163.com> X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: d9t7zmkj8qgnutighxrug71c5orkmhh3 X-Rspamd-Queue-Id: B3AB0C0010 X-HE-Tag: 1786284224-571542 X-HE-Meta: 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 ZWLyyiCt m1ZwdIqBY0EiDiHbFZdTgD4HPE7hwAgoOeJ7Dy87gkeSp12+5uzfIiRDP7iAkSUIxuder6pijeFVFSgg232sOmByMYyhHFjBW2QJ2KaVC64JidPF9P54SCXPJENnb1fN/6H/OeZCWz+u5gRtMZWhaIHZVHomp5iHRqRYMuT9bZcUbt2saliRLT0ekqS2ogpGyYGHuZMfmF2eDZO1VLde6XDOaa8/ax5I1rOI0P+H/Z/Ci4VR/PHcu+Sn8oetjmzY5HjcHC6Yc1XDJnriUa4vyCw4mZ4vUfW9R3bNdVxrESZoYKtA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi, On Sun, Aug 09, 2026 at 08:31:19PM +0800, Longlong Xia wrote: > From: Longlong Xia > > alloc_large_system_hash() allows up to 2^31 buckets, so log2qty can > reach 31. At that limit, the current expression relies on signed > integer wrapping to produce the unsigned hash mask. > > Use an unsigned literal so the mask is computed with unsigned > arithmetic. Supported compiler settings already produce the same > result, so this is a source-level cleanup with no functional change. If complier already takes care of this then why do we want this patch? > Assisted-by: Codex:gpt-5.6-sol > Signed-off-by: Longlong Xia > --- > mm/mm_init.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/mm_init.c b/mm/mm_init.c > index 498d62c4ece3..1883fe923ffb 100644 > --- a/mm/mm_init.c > +++ b/mm/mm_init.c > @@ -2469,7 +2469,7 @@ void *__init alloc_large_system_hash(const char *tablename, > if (_hash_shift) > *_hash_shift = log2qty; > if (_hash_mask) > - *_hash_mask = (1 << log2qty) - 1; > + *_hash_mask = (1U << log2qty) - 1; > > return table; > } > -- > 2.43.0 > -- Sincerely yours, Mike.