On Wed, 2012-03-21 at 08:28 +1100, Benjamin Herrenschmidt wrote: > On Tue, 2012-03-20 at 12:01 -0400, Kautuk Consul wrote: > > Commit d065bd810b6deb67d4897a14bfe21f8eb526ba99 > > (mm: retry page fault when blocking on disk transfer) and > > commit 37b23e0525d393d48a7d59f870b3bc061a30ccdb > > (x86,mm: make pagefault killable) > > > > The above commits introduced changes into the x86 pagefault handler > > for making the page fault handler retryable as well as killable. > > > > These changes reduce the mmap_sem hold time, which is crucial > > during OOM killer invocation. > > > > Port these changes to powerpc. > > I have done that port already :-) It's in powerpc-next which I will send > to Linus to pull today or tomorrow....
BTW. Feel free to review what I've done, it's quite possible that I have screwed something up ... Cheers, Ben. > Cheers, > Ben. > > > Signed-off-by: Mohd. Faris <[email protected]> > > Signed-off-by: Kautuk Consul <[email protected]> > > --- > > arch/powerpc/mm/fault.c | 51 > > +++++++++++++++++++++++++++++++++------------- > > 1 files changed, 36 insertions(+), 15 deletions(-) > > > > diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c > > index 2f0d1b0..a3b1176 100644 > > --- a/arch/powerpc/mm/fault.c > > +++ b/arch/powerpc/mm/fault.c > > @@ -129,6 +129,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, > > unsigned long address, > > int is_write = 0, ret; > > int trap = TRAP(regs); > > int is_exec = trap == 0x400; > > + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; > > > > #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) > > /* > > @@ -212,6 +213,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, > > unsigned long address, > > if (!user_mode(regs) && !search_exception_tables(regs->nip)) > > goto bad_area_nosemaphore; > > > > +retry: > > down_read(&mm->mmap_sem); > > } > > > > @@ -313,6 +315,7 @@ good_area: > > } else if (is_write) { > > if (!(vma->vm_flags & VM_WRITE)) > > goto bad_area; > > + flags |= FAULT_FLAG_WRITE; > > /* a read */ > > } else { > > /* protection fault */ > > @@ -327,7 +330,11 @@ good_area: > > * make sure we exit gracefully rather than endlessly redo > > * the fault. > > */ > > - ret = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : > > 0); > > + ret = handle_mm_fault(mm, vma, address, flags); > > + > > + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) > > + return 0; > > + > > if (unlikely(ret & VM_FAULT_ERROR)) { > > if (ret & VM_FAULT_OOM) > > goto out_of_memory; > > @@ -335,22 +342,36 @@ good_area: > > goto do_sigbus; > > BUG(); > > } > > - if (ret & VM_FAULT_MAJOR) { > > - current->maj_flt++; > > - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, > > - regs, address); > > -#ifdef CONFIG_PPC_SMLPAR > > - if (firmware_has_feature(FW_FEATURE_CMO)) { > > - preempt_disable(); > > - get_lppaca()->page_ins += (1 << PAGE_FACTOR); > > - preempt_enable(); > > + if (flags & FAULT_FLAG_ALLOW_RETRY) { > > + if (ret & VM_FAULT_MAJOR) { > > + current->maj_flt++; > > + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, > > + regs, address); > > +#ifdef CONFIG_PPC_SMLPAR > > + if (firmware_has_feature(FW_FEATURE_CMO)) { > > + preempt_disable(); > > + get_lppaca()->page_ins += (1 << PAGE_FACTOR); > > + preempt_enable(); > > + } > > +#endif > > + } else { > > + current->min_flt++; > > + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, > > + regs, address); > > + } > > + if (fault & VM_FAULT_RETRY) { > > + flags &= ~FAULT_FLAG_ALLOW_RETRY; > > + > > + /* > > + * No need to up_read(&mm->mmap_sem) as we would > > + * have already released it in __lock_page_or_retry > > + * in mm/filemap.c. > > + */ > > + > > + goto retry; > > } > > -#endif > > - } else { > > - current->min_flt++; > > - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, > > - regs, address); > > } > > + > > up_read(&mm->mmap_sem); > > return 0; > > > _______________________________________________ Linuxppc-dev mailing list [email protected] https://lists.ozlabs.org/listinfo/linuxppc-dev
