From: Jane Chu <jane.chu@oracle.com> mainline inclusion from mainline-v6.11-rc1 commit aa298fdf535d47df1279b12a0212deb2389f709a category: feature bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICTDP9 CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Patch series "Enhance soft hwpoison handling and injection", v4. This series is aimed at the following enhancements: - 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. - 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. - 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 5): 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 memory-failure handler invokes kill_accessing_process() to kill the process immediately. So let's take out the '!unmap_success' factor and try to deliver SIGBUS if possible. Link: https://lkml.kernel.org/r/20240524215306.2705454-1-jane.chu@oracle.com Link: https://lkml.kernel.org/r/20240524215306.2705454-2-jane.chu@oracle.com Signed-off-by: Jane Chu <jane.chu@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Cc: Oscar Salvador <oalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Conflicts: mm/memory-failure.c [context conflict] Signed-off-by: Tong Tiangen <tongtiangen@huawei.com> --- mm/memory-failure.c | 15 ++++----------- 1 file changed, 4 insertions(+), 11 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 7f7b75611869..b05946e0776e 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -517,22 +517,15 @@ void add_to_kill_ksm(struct task_struct *tsk, struct page *p, * * Only do anything when FORCEKILL is set, otherwise just free the * list (this is used for clean pages which do not need killing) - * 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, @@ -1661,7 +1654,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn, */ 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; } @@ -1725,7 +1718,7 @@ 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); } /* -- 2.25.1