Re: [PATCH 09/10] riscv: fix livelock in uaccess
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- To: Al Viro <viro@xxxxxxxxxxxxxxxxxx>, linux-arch@xxxxxxxxxxxxxxx
- Subject: Re: [PATCH 09/10] riscv: fix livelock in uaccess
- From: Björn Töpel <bjorn@xxxxxxxxxx>
- Date: Mon, 06 Feb 2023 21:06:31 +0100
- Cc: linux-alpha@xxxxxxxxxxxxxxx, linux-ia64@xxxxxxxxxxxxxxx, linux-hexagon@xxxxxxxxxxxxxxx, linux-m68k@xxxxxxxxxxxxxxx, Michal Simek <monstr@xxxxxxxxx>, Dinh Nguyen <dinguyen@xxxxxxxxxx>, openrisc@xxxxxxxxxxxxxxxxxxxx, linux-parisc@xxxxxxxxxxxxxxx, linux-riscv@xxxxxxxxxxxxxxxxxxx, sparclinux@xxxxxxxxxxxxxxx, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>, Mark Rutland <mark.rutland@xxxxxxx>
- In-reply-to: <Y9l02DvS6CYThTEG@ZenIV>
- References: <Y9lz6yk113LmC9SI@ZenIV> <Y9l02DvS6CYThTEG@ZenIV>
Al Viro <viro@xxxxxxxxxxxxxxxxxx> writes:
> riscv equivalent of 26178ec11ef3 "x86: mm: consolidate VM_FAULT_RETRY handling"
> If e.g. get_user() triggers a page fault and a fatal signal is caught, we might
> end up with handle_mm_fault() returning VM_FAULT_RETRY and not doing anything
> to page tables. In such case we must *not* return to the faulting insn -
> that would repeat the entire thing without making any progress; what we need
> instead is to treat that as failed (user) memory access.
>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Reproduced with Mark's userland program -- thanks!
Tested-by: Björn Töpel <bjorn@xxxxxxxxxx>
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