| Message ID | 20221021200120.175753-3-tony.luck@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Copy-on-write poison recovery | expand |
On 2022/10/22 4:01, Tony Luck wrote: > Cannot call memory_failure() directly from the fault handler because > mmap_lock (and others) are held. Could you please explain which lock makes it unfeasible to call memory_failure() directly and why? I'm somewhat confused. But I agree using memory_failure_queue() should be a good idea. > > It is important, but not urgent, to mark the source page as h/w poisoned > and unmap it from other tasks. > > Use memory_failure_queue() to request a call to memory_failure() for the > page with the error. > > Also provide a stub version for CONFIG_MEMORY_FAILURE=n > > Signed-off-by: Tony Luck <tony.luck@intel.com> > --- > include/linux/mm.h | 5 ++++- > mm/memory.c | 4 +++- > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 8bbcccbc5565..03ced659eb58 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3268,7 +3268,6 @@ enum mf_flags { > int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, > unsigned long count, int mf_flags); > extern int memory_failure(unsigned long pfn, int flags); > -extern void memory_failure_queue(unsigned long pfn, int flags); > extern void memory_failure_queue_kick(int cpu); > extern int unpoison_memory(unsigned long pfn); > extern int sysctl_memory_failure_early_kill; > @@ -3277,8 +3276,12 @@ extern void shake_page(struct page *p); > extern atomic_long_t num_poisoned_pages __read_mostly; > extern int soft_offline_page(unsigned long pfn, int flags); > #ifdef CONFIG_MEMORY_FAILURE > +extern void memory_failure_queue(unsigned long pfn, int flags); > extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags); > #else > +static inline void memory_failure_queue(unsigned long pfn, int flags) > +{ > +} > static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) > { > return 0; > diff --git a/mm/memory.c b/mm/memory.c > index b6056eef2f72..eae242351726 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2866,8 +2866,10 @@ static inline int __wp_page_copy_user(struct page *dst, struct page *src, > unsigned long addr = vmf->address; > > if (likely(src)) { > - if (copy_mc_user_highpage(dst, src, addr, vma)) > + if (copy_mc_user_highpage(dst, src, addr, vma)) { > + memory_failure_queue(page_to_pfn(src), 0); It seems MF_ACTION_REQUIRED is not needed for memory_failure_queue() here. Thanks for your patch. Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Thanks, Miaohe Lin
>> Cannot call memory_failure() directly from the fault handler because >> mmap_lock (and others) are held. > > Could you please explain which lock makes it unfeasible to call memory_failure() directly and > why? I'm somewhat confused. But I agree using memory_failure_queue() should be a good idea. I tried calling memory_failure() directly, and my system just hung. I made the assumption that it had deadlocked based somewhat on the comments in mm/memory.c about mmap_lock being held ... but I didn't dig into what had gone wrong. -Tony
On 2022/10/29 0:13, Luck, Tony wrote: >>> Cannot call memory_failure() directly from the fault handler because >>> mmap_lock (and others) are held. >> >> Could you please explain which lock makes it unfeasible to call memory_failure() directly and >> why? I'm somewhat confused. But I agree using memory_failure_queue() should be a good idea. > > I tried calling memory_failure() directly, and my system just hung. I made the assumption > that it had deadlocked based somewhat on the comments in mm/memory.c about mmap_lock > being held ... but I didn't dig into what had gone wrong. I see. Thanks for your explanation. :) > > -Tony >
diff --git a/include/linux/mm.h b/include/linux/mm.h index 8bbcccbc5565..03ced659eb58 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3268,7 +3268,6 @@ enum mf_flags { int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, unsigned long count, int mf_flags); extern int memory_failure(unsigned long pfn, int flags); -extern void memory_failure_queue(unsigned long pfn, int flags); extern void memory_failure_queue_kick(int cpu); extern int unpoison_memory(unsigned long pfn); extern int sysctl_memory_failure_early_kill; @@ -3277,8 +3276,12 @@ extern void shake_page(struct page *p); extern atomic_long_t num_poisoned_pages __read_mostly; extern int soft_offline_page(unsigned long pfn, int flags); #ifdef CONFIG_MEMORY_FAILURE +extern void memory_failure_queue(unsigned long pfn, int flags); extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags); #else +static inline void memory_failure_queue(unsigned long pfn, int flags) +{ +} static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) { return 0; diff --git a/mm/memory.c b/mm/memory.c index b6056eef2f72..eae242351726 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2866,8 +2866,10 @@ static inline int __wp_page_copy_user(struct page *dst, struct page *src, unsigned long addr = vmf->address; if (likely(src)) { - if (copy_mc_user_highpage(dst, src, addr, vma)) + if (copy_mc_user_highpage(dst, src, addr, vma)) { + memory_failure_queue(page_to_pfn(src), 0); return -EHWPOISON; + } return 0; }
Cannot call memory_failure() directly from the fault handler because mmap_lock (and others) are held. It is important, but not urgent, to mark the source page as h/w poisoned and unmap it from other tasks. Use memory_failure_queue() to request a call to memory_failure() for the page with the error. Also provide a stub version for CONFIG_MEMORY_FAILURE=n Signed-off-by: Tony Luck <tony.luck@intel.com> --- include/linux/mm.h | 5 ++++- mm/memory.c | 4 +++- 2 files changed, 7 insertions(+), 2 deletions(-)