| Message ID | Y9l02DvS6CYThTEG@ZenIV (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | d835eb3a57de50d16dd4a6b53f95dbc2bfa8ef48 |
| Delegated to: | Palmer Dabbelt |
| Headers | show |
| Series | [01/10] alpha: fix livelock in uaccess | expand |
| Context | Check | Description |
|---|---|---|
| conchuod/cover_letter | warning | Series does not have a cover letter |
| conchuod/tree_selection | success | Guessed tree name to be for-next |
| conchuod/fixes_present | success | Fixes tag not required for -next series |
| conchuod/maintainers_pattern | success | MAINTAINERS pattern errors before the patch: 13 and now 13 |
| conchuod/verify_signedoff | success | Signed-off-by tag matches author and committer |
| conchuod/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/build_rv64_clang_allmodconfig | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/module_param | success | Was 0 now: 0 |
| conchuod/build_rv64_gcc_allmodconfig | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/alphanumeric_selects | success | Out of order selects before the patch: 57 and now 57 |
| conchuod/build_rv32_defconfig | success | Build OK |
| conchuod/dtb_warn_rv64 | success | Errors and warnings before: 2 this patch: 2 |
| conchuod/header_inline | success | No static functions without inline keyword in header files |
| conchuod/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 12 lines checked |
| conchuod/source_inline | success | Was 0 now: 0 |
| conchuod/build_rv64_nommu_k210_defconfig | success | Build OK |
| conchuod/verify_fixes | success | No Fixes tag |
| conchuod/build_rv64_nommu_virt_defconfig | success | Build OK |
Al Viro <viro@zeniv.linux.org.uk> 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@zeniv.linux.org.uk> Reproduced with Mark's userland program -- thanks! Tested-by: Björn Töpel <bjorn@kernel.org>
On Tue, Jan 31, 2023 at 9:07 PM Al Viro <viro@zeniv.linux.org.uk> wrote: > 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@zeniv.linux.org.uk> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c index d86f7cebd4a7..c91d85349d39 100644 --- a/arch/riscv/mm/fault.c +++ b/arch/riscv/mm/fault.c @@ -324,8 +324,11 @@ asmlinkage void do_page_fault(struct pt_regs *regs) * signal first. We do not need to release the mmap_lock because it * would already be released in __lock_page_or_retry in mm/filemap.c. */ - if (fault_signal_pending(fault, regs)) + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + no_context(regs, addr); return; + } /* The fault is fully completed (including releasing mmap lock) */ if (fault & VM_FAULT_COMPLETED)
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@zeniv.linux.org.uk> --- arch/riscv/mm/fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)