zhenwei pi
2022-May-30 05:46 UTC
[PATCH 2/3] mm/memory-failure.c: support reset PTE during unpoison
On 5/30/22 13:02, HORIGUCHI NAOYA(?? ??) wrote:> On Fri, May 20, 2022 at 03:06:47PM +0800, zhenwei pi wrote: >> Origianlly, unpoison_memory() is only used by hwpoison-inject, and >> unpoisons a page which is poisoned by hwpoison-inject too. The kernel PTE >> entry has no change during software poison/unpoison. >> >> On a virtualization platform, it's possible to fix hardware corrupted page >> by hypervisor, typically the hypervisor remaps the error HVA(host virtual >> address). So add a new parameter 'const char *reason' to show the reason >> called by. >> >> Once the corrupted page gets fixed, the guest kernel needs put page to >> buddy. Reuse the page and hit the following issue(Intel Platinum 8260): >> BUG: unable to handle page fault for address: ffff888061646000 >> #PF: supervisor write access in kernel mode >> #PF: error_code(0x0002) - not-present page >> PGD 2c01067 P4D 2c01067 PUD 61aaa063 PMD 10089b063 PTE 800fffff9e9b9062 >> Oops: 0002 [#1] PREEMPT SMP NOPTI >> CPU: 2 PID: 31106 Comm: stress Kdump: loaded Tainted: G M OE 5.18.0-rc6.bm.1-amd64 #6 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 >> RIP: 0010:clear_page_erms+0x7/0x10 >> >> The kernel PTE entry of the fixed page is still uncorrected, kernel hits >> page fault during prep_new_page. So add 'bool reset_kpte' to get a change >> to fix the PTE entry if the page is fixed by hypervisor. >> >> Signed-off-by: zhenwei pi <pizhenwei at bytedance.com> >> --- >> include/linux/mm.h | 2 +- >> mm/hwpoison-inject.c | 2 +- >> mm/memory-failure.c | 26 +++++++++++++++++++------- >> 3 files changed, 21 insertions(+), 9 deletions(-) >> > > Do you need undoing rate limiting here? In the original unpoison's usage, > avoiding flood of "Unpoison: Software-unpoisoned page" messages is helpful. > > And unpoison seems to be called from virtio-balloon multiple times when > the backend is 2MB hugepages. If it's right, printing out 512 lines of > "Unpoison: Unpoisoned page 0xXXX by virtio-balloon" messages might not be > so helpful? >All the suggestions(include '[PATCH 1/3] memory-failure: Introduce memory failure notifier') are reasonable, I'll fix them in the next version. Thanks a lot! -- zhenwei pi