Re: [PATCH v2] x86/fault: Send a SIGBUS to user process always for hwpoison page access.
From: HORIGUCHI NAOYA (堀口 直也) <hidden>
Date: 2021-02-04 07:29:02
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Hi Aili, On Mon, Feb 01, 2021 at 04:17:49PM +0800, Aili Yao wrote:
When one page is already hwpoisoned by AO action, process may not be killed, the process mapping this page may make a syscall include this page and result to trigger a VM_FAULT_HWPOISON fault, if it's in kernel mode it may be fixed by fixup_exception. Current code will just return error code to user process. This is not sufficient, we should send a SIGBUS to the process and log the info to console, as we can't trust the process will handle the error correctly. Suggested-by: Feng Yang <redacted> Signed-off-by: Aili Yao <redacted> ---
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quoted hunk ↗ jump to hunk
@@ -662,12 +662,32 @@ no_context(struct pt_regs *regs, unsigned long error_code, * In this case we need to make sure we're not recursively * faulting through the emulate_vsyscall() logic. */ + + if (IS_ENABLED(CONFIG_MEMORY_FAILURE) && + fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) { + unsigned int lsb = 0; + + pr_err("MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n", + current->comm, current->pid, address); + + sanitize_error_code(address, &error_code); + set_signal_archinfo(address, error_code); + + if (fault & VM_FAULT_HWPOISON_LARGE) + lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); + if (fault & VM_FAULT_HWPOISON) + lsb = PAGE_SHIFT; + + force_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb);
This part contains some duplicated code with do_sigbus(), so some refactoring (like adding a common function) would be more helpful. Thanks, Naoya Horiguchi