Re: Regression: Fwd: Re: [PATCH] riscv: mmap with PROT_WRITE but no PROT_READ is invalid

From: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
To: Conor Dooley <conor@kernel.org>
Cc: regressions@lists.linux.dev, stable@vger.kernel.org,
	Eva Kotova <nyandarknessgirl@gmail.com>,
	linux-riscv@lists.infradead.org, coelacanthus@outlook.com,
	kernel-team@lists.ubuntu.com
Subject: Re: Regression: Fwd: Re: [PATCH] riscv: mmap with PROT_WRITE but no PROT_READ is invalid
Date: Tue, 11 Oct 2022 18:18:54 +0100	[thread overview]
Message-ID: <CADWks+Y3xYc325x2_2jeRh-iyE6i0gi2Ldd_KKBLhB7s9nQhWA@mail.gmail.com> (raw)
In-Reply-To: <Y0WgwBgenhnk7/O2@spud>

On Tue, 11 Oct 2022 at 17:58, Conor Dooley <conor@kernel.org> wrote:
>
> On Tue, Oct 11, 2022 at 05:52:13PM +0100, Dimitri John Ledkov wrote:
> > #regzbot ^introduced 2139619bcad7ac44cc8f6f749089120594056613
> >
> > Over at https://lore.kernel.org/linux-riscv/Yz80ewHKTPI5Rvuz@spud/T/#ebde47064434d4ca4807b4abb8eb39898c48a8de2
> > it is reported that 2139619bcad7ac44cc8f6f749089120594056613
> > regresses userspace (openjdk) on riscv64.
> >
> > This commit has already been released in v6.0 kernel upstream,
> > but has also been included in the stable patch series all the
> > way back to v4.19.y
> >
> > There is a proposed fix for this at
> > https://lore.kernel.org/linux-riscv/20220915193702.2201018-1-abrestic@rivosinc.com/
> > which has not yet been merged upstream or in stable series.
> >
> > Please review and merge above proposed fix, or please revert
> > 2139619bcad7ac44cc8f6f749089120594056613 to stop the regression
> > spreading to all the distributions.
>
> Out of curiosity, and given the CC list lacks a CC of the maintainer,
> who are you actually asking to review and/or merge this?
>

Good point, this is my first time escalating a regression which is now
in all the stable trees. I guess I should have CC'ed all the M: from
RISC-V in the Maintainers file. Not just the riscv list.

> I'll go bump the fix itself.

Thanks.

>
> Thanks,
> Conor.
>
> >
> > In Ubuntu this regression will be tracked as https://bugs.launchpad.net/bugs/+bug/1992484
> >
> > -------- Forwarded Message --------
> > Subject: Re: [PATCH] riscv: mmap with PROT_WRITE but no PROT_READ is invalid
> > Date: Thu, 6 Oct 2022 22:20:02 +0300
> > From: Eva Kotova <nyandarknessgirl@gmail.com>
> > Reply-To: PH7PR14MB559464DBDD310E755F5B21E8CEDC9@PH7PR14MB5594.namprd14.prod.outlook.com
> > To: coelacanthus@outlook.com
> > CC: c141028@gmail.com, dramforever@live.com, linux-riscv@lists.infradead.org, palmer@dabbelt.com, xc-tan@outlook.com
> >
> > On Tue, 31 May 2022 00:56:52 PDT (-0700), coelacanthus@outlook.com wrote:
> > > As mentioned in Table 4.5 in RISC-V spec Volume 2 Section 4.3, write
> > > but not read is "Reserved for future use.". For now, they are not valid.
> > > In the current code, -wx is marked as invalid, but -w- is not marked
> > > as invalid.
> >
> > This patch breaks OpenJDK/Java on RISC-V, as it tries to create a w-only
> > protective page:
> >
> > #
> > # There is insufficient memory for the Java Runtime Environment to continue.
> > # Native memory allocation (mmap) failed to map 4096 bytes for failed to
> > allocate memory for PaX check.
> > # An error report file with more information is saved as:
> > # /root/hs_err_pid107.log
> >
> > I bisected to this commit since on Linux 5.19+ java no longer works.
> > Perhaps some fallback should be implemented, to prevent userspace
> > breakage. It is currently documented, that at least on i386 PROT_WRITE
> > mappings imply PROT_READ (See man mmap(2) NOTES), this would be a good
> > place to start.
> >
> > Best regards,
> > Eva
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
> >
>
>
>

-- 
okurrr,

Dimitri