diff options
| author | Jane Chu <jane.chu@oracle.com> | 2024-05-01 17:24:56 -0600 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-05-07 11:29:48 -0700 |
| commit | d69c5a07dc2c755110f675763745c18fe937edb7 (patch) | |
| tree | f7af23c3a048af8adcc3a3fb4f9fb15b5be0ce41 | |
| parent | c8fdc705145013e5ea336dd34c46e07c33a5bb36 (diff) | |
mm/memory-failure: try to send SIGBUS even if unmap failed
Patch series "Enhance soft hwpoison handling and injection".
This series aim at the following enhancement -
1. Let one hwpoison injector, that is, madvise(MADV_HWPOISON) to behave
more like as if a real UE occurred. Because the other two injectors
such as hwpoison-inject and the 'einj' on x86 can't, and it seems to
me we need a better simulation to real UE scenario.
2. For years, if the kernel is unable to unmap a hwpoisoned page, it send
a SIGKILL instead of SIGBUS to prevent user process from potentially
accessing the page again. But in doing so, the user process also lose
important information: vaddr, for recovery. Fortunately, the kernel
already has code to kill process re-accessing a hwpoisoned page, so
remove the '!unmap_success' check.
3. Right now, if a thp page under GUP longterm pin is hwpoisoned, and
kernel cannot split the thp page, memory-failure simply ignores
the UE and returns. That's not ideal, it could deliver a SIGBUS with
useful information for userspace recovery.
This patch (of 3):
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.
Link: https://lkml.kernel.org/r/20240501232458.3919593-1-jane.chu@oracle.com
Link: https://lkml.kernel.org/r/20240501232458.3919593-2-jane.chu@oracle.com
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/memory-failure.c | 13 |
1 files changed, 4 insertions, 9 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 16ada4fb02b7..d73d03ef721e 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -517,19 +517,14 @@ 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, @@ -1660,7 +1655,7 @@ static bool hwpoison_user_mappings(struct folio *folio, struct page *p, */ forcekill = folio_test_dirty(folio) || (flags & MF_MUST_KILL) || !unmap_success; - kill_procs(&tokill, forcekill, !unmap_success, pfn, flags); + kill_procs(&tokill, forcekill, pfn, flags); return unmap_success; } @@ -1724,7 +1719,7 @@ 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); } /* |