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

[Conor Dooley]

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?

I'll go bump the fix itself.

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 at gmail.com>
> Reply-To: PH7PR14MB559464DBDD310E755F5B21E8CEDC9 at PH7PR14MB5594.namprd14.prod.outlook.com
> To: coelacanthus at outlook.com
> CC: c141028 at gmail.com, dramforever at live.com, linux-riscv at lists.infradead.org, palmer at dabbelt.com, xc-tan at outlook.com
> 
> On Tue, 31 May 2022 00:56:52 PDT (-0700), coelacanthus at 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
> 
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