Messages in this thread | | | Date | Thu, 9 May 2024 09:40:31 -0700 | Subject | Re: [PATCH 1/3] mm/memory-failure: try to send SIGBUS even if unmap failed | From | Jane Chu <> |
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On 5/8/2024 7:54 PM, Miaohe Lin wrote:
> On 2024/5/2 7:24, Jane Chu wrote: >> For years when it comes down to kill a process due to hwpoison, >> a SIGBUS is delivered only if unmap has been successful. >> Otherwise, a SIGKILL is delivered. And the reason for that is >> to prevent the involved process from accessing the hwpoisoned >> page again. >> >> Since then a lot has changed, a hwpoisoned page is marked and >> upon being re-accessed, the process will be killed immediately. >> So let's take out the '!unmap_success' factor and try to deliver >> SIGBUS if possible. >> >> Signed-off-by: Jane Chu <jane.chu@oracle.com> >> --- >> mm/memory-failure.c | 13 ++++--------- >> 1 file changed, 4 insertions(+), 9 deletions(-) >> >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >> index 9e62a00b46dd..7fcf182abb96 100644 >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> @@ -519,19 +519,14 @@ void add_to_kill_ksm(struct task_struct *tsk, struct page *p, >> * Also when FAIL is set do a force kill because something went >> * wrong earlier. >> */ >> -static void kill_procs(struct list_head *to_kill, int forcekill, bool fail, >> +static void kill_procs(struct list_head *to_kill, int forcekill, >> unsigned long pfn, int flags) >> { >> struct to_kill *tk, *next; >> >> list_for_each_entry_safe(tk, next, to_kill, nd) { >> if (forcekill) { >> - /* >> - * In case something went wrong with munmapping >> - * make sure the process doesn't catch the >> - * signal and then access the memory. Just kill it. >> - */ >> - if (fail || tk->addr == -EFAULT) { >> + if (tk->addr == -EFAULT) { >> pr_err("%#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n", >> pfn, tk->tsk->comm, tk->tsk->pid); >> do_send_sig_info(SIGKILL, SEND_SIG_PRIV, >> @@ -1666,7 +1661,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn, >> */ > There is comment above the forcekill saying: > > When there was a problem unmapping earlier use a more force-full > uncatchable kill to prevent any accesses to the poisoned memory. > > This might need to be changed too.
Yes, will do.
thanks!
-jane
> Thanks. > . > >> forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL) || >> !unmap_success; >> - kill_procs(&tokill, forcekill, !unmap_success, pfn, flags); >> + kill_procs(&tokill, forcekill, pfn, flags); >> >> return unmap_success; >> } >> @@ -1730,7 +1725,7 @@ static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn, >> unmap_mapping_range(mapping, start, size, 0); >> } >> >> - kill_procs(to_kill, flags & MF_MUST_KILL, false, pfn, flags); >> + kill_procs(to_kill, flags & MF_MUST_KILL, pfn, flags); >> } >> >> /* >> >
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