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Date: Fri, 6 Sep 2019 10:51:50 +0200
From: David Hildenbrand <david@...hat.com>
To: Peter Xu <peterx@...hat.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Cc: Hugh Dickins <hughd@...gle.com>, Maya Gokhale <gokhale2@...l.gov>,
Jerome Glisse <jglisse@...hat.com>,
Pavel Emelyanov <xemul@...tuozzo.com>,
Johannes Weiner <hannes@...xchg.org>,
Martin Cracauer <cracauer@...s.org>,
Marty McFadden <mcfadden8@...l.gov>, Shaohua Li <shli@...com>,
Andrea Arcangeli <aarcange@...hat.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Denis Plotnikov <dplotnikov@...tuozzo.com>,
Mike Rapoport <rppt@...ux.vnet.ibm.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Mel Gorman <mgorman@...e.de>,
"Kirill A . Shutemov" <kirill@...temov.name>,
"Dr . David Alan Gilbert" <dgilbert@...hat.com>
Subject: Re: [PATCH v2 2/7] mm: Introduce FAULT_FLAG_DEFAULT
On 05.09.19 12:15, Peter Xu wrote:
> Although there're tons of arch-specific page fault handlers, most of
> them are still sharing the same initial value of the page fault flags.
> Say, merely all of the page fault handlers would allow the fault to be
> retried, and they also allow the fault to respond to SIGKILL.
>
> Let's define a default value for the fault flags to replace those
> initial page fault flags that were copied over. With this, it'll be
> far easier to introduce new fault flag that can be used by all the
> architectures instead of touching all the archs.
>
> Signed-off-by: Peter Xu <peterx@...hat.com>
> ---
> arch/alpha/mm/fault.c | 2 +-
> arch/arc/mm/fault.c | 2 +-
> arch/arm/mm/fault.c | 2 +-
> arch/arm64/mm/fault.c | 2 +-
> arch/hexagon/mm/vm_fault.c | 2 +-
> arch/ia64/mm/fault.c | 2 +-
> arch/m68k/mm/fault.c | 2 +-
> arch/microblaze/mm/fault.c | 2 +-
> arch/mips/mm/fault.c | 2 +-
> arch/nds32/mm/fault.c | 2 +-
> arch/nios2/mm/fault.c | 2 +-
> arch/openrisc/mm/fault.c | 2 +-
> arch/parisc/mm/fault.c | 2 +-
> arch/powerpc/mm/fault.c | 2 +-
> arch/riscv/mm/fault.c | 2 +-
> arch/s390/mm/fault.c | 2 +-
> arch/sh/mm/fault.c | 2 +-
> arch/sparc/mm/fault_32.c | 2 +-
> arch/sparc/mm/fault_64.c | 2 +-
> arch/um/kernel/trap.c | 2 +-
> arch/unicore32/mm/fault.c | 2 +-
> arch/x86/mm/fault.c | 2 +-
> arch/xtensa/mm/fault.c | 2 +-
> include/linux/mm.h | 7 +++++++
> 24 files changed, 30 insertions(+), 23 deletions(-)
>
> diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
> index 741e61ef9d3f..de4cc6936391 100644
> --- a/arch/alpha/mm/fault.c
> +++ b/arch/alpha/mm/fault.c
> @@ -89,7 +89,7 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
> const struct exception_table_entry *fixup;
> int si_code = SEGV_MAPERR;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> /* As of EV6, a load into $31/$f31 is a prefetch, and never faults
> (or is suppressed by the PALcode). Support that for older CPUs
> diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
> index 3861543b66a0..61919e4e4eec 100644
> --- a/arch/arc/mm/fault.c
> +++ b/arch/arc/mm/fault.c
> @@ -94,7 +94,7 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
> (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
> exec = 1;
>
> - flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + flags = FAULT_FLAG_DEFAULT;
> if (user_mode(regs))
> flags |= FAULT_FLAG_USER;
> if (write)
> diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
> index 890eeaac3cbb..2ae28ffec622 100644
> --- a/arch/arm/mm/fault.c
> +++ b/arch/arm/mm/fault.c
> @@ -241,7 +241,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
> struct mm_struct *mm;
> int sig, code;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> if (kprobe_page_fault(regs, fsr))
> return 0;
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index cfd65b63f36f..613e7434c208 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -410,7 +410,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
> struct mm_struct *mm = current->mm;
> vm_fault_t fault, major = 0;
> unsigned long vm_flags = VM_READ | VM_WRITE;
> - unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int mm_flags = FAULT_FLAG_DEFAULT;
>
> if (kprobe_page_fault(regs, esr))
> return 0;
> diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
> index b3bc71680ae4..223787e01bdd 100644
> --- a/arch/hexagon/mm/vm_fault.c
> +++ b/arch/hexagon/mm/vm_fault.c
> @@ -41,7 +41,7 @@ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
> int si_code = SEGV_MAPERR;
> vm_fault_t fault;
> const struct exception_table_entry *fixup;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> /*
> * If we're in an interrupt or have no user context,
> diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
> index c2f299fe9e04..d039b846f671 100644
> --- a/arch/ia64/mm/fault.c
> +++ b/arch/ia64/mm/fault.c
> @@ -65,7 +65,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
> struct mm_struct *mm = current->mm;
> unsigned long mask;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> mask = ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
> | (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
> diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
> index e9b1d7585b43..8e734309ace9 100644
> --- a/arch/m68k/mm/fault.c
> +++ b/arch/m68k/mm/fault.c
> @@ -71,7 +71,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
> struct mm_struct *mm = current->mm;
> struct vm_area_struct * vma;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
> regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
> diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
> index e6a810b0c7ad..45c9f66c1dbc 100644
> --- a/arch/microblaze/mm/fault.c
> +++ b/arch/microblaze/mm/fault.c
> @@ -91,7 +91,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
> int code = SEGV_MAPERR;
> int is_write = error_code & ESR_S;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> regs->ear = address;
> regs->esr = error_code;
> diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
> index f589aa8f47d9..6660b77ff8f3 100644
> --- a/arch/mips/mm/fault.c
> +++ b/arch/mips/mm/fault.c
> @@ -44,7 +44,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
> const int field = sizeof(unsigned long) * 2;
> int si_code;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
>
> diff --git a/arch/nds32/mm/fault.c b/arch/nds32/mm/fault.c
> index 064ae5d2159d..a40de112a23a 100644
> --- a/arch/nds32/mm/fault.c
> +++ b/arch/nds32/mm/fault.c
> @@ -76,7 +76,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
> int si_code;
> vm_fault_t fault;
> unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> error_code = error_code & (ITYPE_mskINST | ITYPE_mskETYPE);
> tsk = current;
> diff --git a/arch/nios2/mm/fault.c b/arch/nios2/mm/fault.c
> index 6a2e716b959f..a401b45cae47 100644
> --- a/arch/nios2/mm/fault.c
> +++ b/arch/nios2/mm/fault.c
> @@ -47,7 +47,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause,
> struct mm_struct *mm = tsk->mm;
> int code = SEGV_MAPERR;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> cause >>= 2;
>
> diff --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c
> index 5d4d3a9691d0..fd1592a56238 100644
> --- a/arch/openrisc/mm/fault.c
> +++ b/arch/openrisc/mm/fault.c
> @@ -50,7 +50,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
> struct vm_area_struct *vma;
> int si_code;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> tsk = current;
>
> diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
> index adbd5e2144a3..355e3e13fa72 100644
> --- a/arch/parisc/mm/fault.c
> +++ b/arch/parisc/mm/fault.c
> @@ -274,7 +274,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
> if (!mm)
> goto no_context;
>
> - flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + flags = FAULT_FLAG_DEFAULT;
> if (user_mode(regs))
> flags |= FAULT_FLAG_USER;
>
> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index 8432c281de92..408ee769c470 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -435,7 +435,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
> {
> struct vm_area_struct * vma;
> struct mm_struct *mm = current->mm;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
> int is_exec = TRAP(regs) == 0x400;
> int is_user = user_mode(regs);
> int is_write = page_fault_is_write(error_code);
> diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
> index 96add1427a75..deeb820bd855 100644
> --- a/arch/riscv/mm/fault.c
> +++ b/arch/riscv/mm/fault.c
> @@ -28,7 +28,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
> struct vm_area_struct *vma;
> struct mm_struct *mm;
> unsigned long addr, cause;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
> int code = SEGV_MAPERR;
> vm_fault_t fault;
>
> diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
> index 7b0bb475c166..74a77b2bca75 100644
> --- a/arch/s390/mm/fault.c
> +++ b/arch/s390/mm/fault.c
> @@ -429,7 +429,7 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
>
> address = trans_exc_code & __FAIL_ADDR_MASK;
> perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
> - flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + flags = FAULT_FLAG_DEFAULT;
> if (user_mode(regs))
> flags |= FAULT_FLAG_USER;
> if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
> diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
> index 5f51456f4fc7..becf0be267bb 100644
> --- a/arch/sh/mm/fault.c
> +++ b/arch/sh/mm/fault.c
> @@ -380,7 +380,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
> struct mm_struct *mm;
> struct vm_area_struct * vma;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> tsk = current;
> mm = tsk->mm;
> diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
> index 8d69de111470..0863f6fdd2c5 100644
> --- a/arch/sparc/mm/fault_32.c
> +++ b/arch/sparc/mm/fault_32.c
> @@ -168,7 +168,7 @@ asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
> int from_user = !(regs->psr & PSR_PS);
> int code;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> if (text_fault)
> address = regs->pc;
> diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
> index 2371fb6b97e4..a1cba3eef79e 100644
> --- a/arch/sparc/mm/fault_64.c
> +++ b/arch/sparc/mm/fault_64.c
> @@ -267,7 +267,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
> int si_code, fault_code;
> vm_fault_t fault;
> unsigned long address, mm_rss;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> fault_code = get_thread_fault_code();
>
> diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
> index 58fe36856182..bc2756782d64 100644
> --- a/arch/um/kernel/trap.c
> +++ b/arch/um/kernel/trap.c
> @@ -32,7 +32,7 @@ int handle_page_fault(unsigned long address, unsigned long ip,
> pmd_t *pmd;
> pte_t *pte;
> int err = -EFAULT;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> *code_out = SEGV_MAPERR;
>
> diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c
> index 76342de9cf8c..60453c892c51 100644
> --- a/arch/unicore32/mm/fault.c
> +++ b/arch/unicore32/mm/fault.c
> @@ -202,7 +202,7 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
> struct mm_struct *mm;
> int sig, code;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> tsk = current;
> mm = tsk->mm;
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 9ceacd1156db..994c860ac2d8 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -1287,7 +1287,7 @@ void do_user_addr_fault(struct pt_regs *regs,
> struct task_struct *tsk;
> struct mm_struct *mm;
> vm_fault_t fault, major = 0;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> tsk = current;
> mm = tsk->mm;
> diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
> index f81b1478da61..d2b082908538 100644
> --- a/arch/xtensa/mm/fault.c
> +++ b/arch/xtensa/mm/fault.c
> @@ -43,7 +43,7 @@ void do_page_fault(struct pt_regs *regs)
>
> int is_write, is_exec;
> vm_fault_t fault;
> - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> + unsigned int flags = FAULT_FLAG_DEFAULT;
>
> code = SEGV_MAPERR;
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0334ca97c584..57fb5c535f8e 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -393,6 +393,13 @@ extern pgprot_t protection_map[16];
> #define FAULT_FLAG_REMOTE 0x80 /* faulting for non current tsk/mm */
> #define FAULT_FLAG_INSTRUCTION 0x100 /* The fault was during an instruction fetch */
>
> +/*
> + * The default fault flags that should be used by most of the
> + * arch-specific page fault handlers.
> + */
> +#define FAULT_FLAG_DEFAULT (FAULT_FLAG_ALLOW_RETRY | \
> + FAULT_FLAG_KILLABLE)
> +
> #define FAULT_FLAG_TRACE \
> { FAULT_FLAG_WRITE, "WRITE" }, \
> { FAULT_FLAG_MKWRITE, "MKWRITE" }, \
>
Reviewed-by: David Hildenbrand <david@...hat.com>
--
Thanks,
David / dhildenb
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