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b=THmqX8z0XY2vShT+oN+k58cZPc8qtCX0GKKF7CItaFCMczcEQnmyhAEyR63WWJa3Y 0ccps40WBnBLmgZej9zfz4VT5bbR4DP9fVPegZKaSP/9JBi2m+gbkm86fDMiZXrnF3 4J6/hsW8ztkD9j1w2rFlVglS8QyfK0ma6okLNDVQ= Date: Fri, 6 Mar 2026 14:54:34 -0800 From: Andrew Morton To: Josh Law Cc: Liam.Howlett@oracle.com, aliceryhl@google.com, andrewjballance@gmail.com, maple-tree@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Josh Law Subject: Re: [PATCH] lib/maple_tree: fix swapped arguments in mas_safe_pivot() call Message-Id: <20260306145434.c069313fe809d94e64a07109@linux-foundation.org> In-Reply-To: References: <20260306200820.2819999-1-objecting@objecting.org> <20260306133321.4fa6c5a73067bd179a5e888e@linux-foundation.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: AE7A3180005 X-Stat-Signature: j85kk9m9yfhz34t1icu4zc7ncoe9dp4x X-Rspam-User: X-HE-Tag: 1772837676-706443 X-HE-Meta: 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 3MuRJ2dI Xqqa9UxGhOas6Bi5E9EDGiTtpwMfbxthEXCmaEl7n2hIUI0RstBynWcoZOeJKkkj9G67Ii/lpGmElCy5cp5l7Mj0wrRza639D3LJMKdprezBaSbfBcGt75AAygDBqtni/qQA08f6psdoLVS9JivQE+OVA+irdZ+POfhDXbCCzJVLteM/7MeORPm7qa1gbQBrxCV2wI96ZAo3d0+QNDZfwHDyXtmrlghSjWBguYAWJQ1AO3LiMUjviFMJBuDDdUe/Rk6JjziMhTSIYlq+Z99lHR27Ck1yiU6VGRheQj5tixjHyVCSDc3e5ntBN027PM7oTnMLgLAEZTVm0JfnNRHes6WeNeg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 6 Mar 2026 22:11:54 +0000 Josh Law wrote: > >> --- a/lib/maple_tree.c > >> +++ b/lib/maple_tree.c > >> @@ -3279,7 +3279,7 @@ static inline void mas_extend_spanning_null(stru= ct ma_wr_state *l_wr_mas, > >> =A0=A0=A0=A0=A0=A0=A0 (r_mas->last < r_mas->max) && > >> =A0=A0=A0=A0=A0=A0=A0 !mas_slot_locked(r_mas, r_wr_mas->slots, r_mas->= offset + 1)) { > >> =A0=A0=A0=A0=A0=A0=A0 r_mas->last =3D mas_safe_pivot(r_mas, r_wr_mas->= pivots, > >> -=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= r_wr_mas->type, r_mas->offset + 1); > >> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= r_mas->offset + 1, r_wr_mas->type); > >> =A0=A0=A0=A0=A0=A0=A0 r_mas->offset++; > >> =A0=A0=A0 } > > > > Whoops.=A0 How come nobody has noticed after 4+ years? > > > > I'll add > > > > =A0=A0=A0 Fixes: 54a611b60590 ("Maple Tree: add new data structure") > > > > and maybe cc:stable if we have a reason to do so. >=20 > Hi Andrew, on thought, I'd like to add Cc: stable@vger.kernel.org to this. > Even though it's been 4 years, a swapped argument in a core data structur= e like Maple Tree is a silent bug that could cause rare corruption. Better = to defuse it in the LTS kernels. Seems appropriate. But not as a hotfix, given the 3+ year thing. I was hoping to hear some thoughts on why this has proven to be so benign. = =20