On Tue, Jan 31, 2023 at 08:02:51PM +0000, Al Viro wrote:
On x86 it had been noticed and fixed back in 2014, in 26178ec11ef3 "x86: mm: consolidate VM_FAULT_RETRY handling". Some of the other architectures had it dealt with later - e.g. arm in 2017, the fix is 746a272e44141 "ARM: 8692/1: mm: abort uaccess retries upon fatal signal"; xtensa - in 2021, the fix is 7b9acbb6aad4f "xtensa: fix uaccess-related livelock in do_page_fault", etc. However, it never had been done on a bunch of architectures - the current mainline still has that bug on alpha, hexagon, itanic, m68k, microblaze, nios2, openrisc, parisc, riscv and sparc (both sparc32 and sparc64). Fixes are trivial, but I've no way to test them for most of those architectures.
FWIW, when I fixed arm and arm64 back in 2017, I did report the issue here with a test case (and again in 2021, with maintainers all explciitly Cc'd): https://lore.kernel.org/lkml/20170822102527.GA14671@leverpostej/ https://lore.kernel.org/linux-arch/20210121123140.GD48431@C02TD0UTHF1T.local/ ... so if anyone has access to those architectures, that test might be useful for verifying the fix. Thanks, Mark.
