mm: move tlb_flush_pending inline helpers to mm_inline.h

linux/mm_types.h should only define structure definitions, to make it cheap to include elsewhere. The atomic_t helper function definitions are particularly large, so it's better to move the helpers using those into the existing linux/mm_inline.h and only include that where needed. As a follow-up, we may want to go through all the indirect includes in mm_types.h and reduce them as much as possible.

Arnd Bergmann committed 4 years ago

Commit 36090de1 parent 17fca139 files · +137 −130Browse files

Showing the changes to include (3 of 9 files). Show all

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3 files

include/linux/mm.h +0 −45
include/linux/mm_inline.h +86 −0
include/linux/mm_types.h +45 −84

include/linux/mm.h+0−45

@@ -424,51 +424,6 @@ extern unsigned int kobjsize(const void *objp); · 423 unmodified lines
424	424	*/
425	425	extern pgprot_t protection_map[16];
426	426
427		−/**
428		− * enum fault_flag - Fault flag definitions.
429		− * @FAULT_FLAG_WRITE: Fault was a write fault.
430		− * @FAULT_FLAG_MKWRITE: Fault was mkwrite of existing PTE.
431		− * @FAULT_FLAG_ALLOW_RETRY: Allow to retry the fault if blocked.
432		− * @FAULT_FLAG_RETRY_NOWAIT: Don't drop mmap_lock and wait when retrying.
433		− * @FAULT_FLAG_KILLABLE: The fault task is in SIGKILL killable region.
434		− * @FAULT_FLAG_TRIED: The fault has been tried once.
435		− * @FAULT_FLAG_USER: The fault originated in userspace.
436		− * @FAULT_FLAG_REMOTE: The fault is not for current task/mm.
437		− * @FAULT_FLAG_INSTRUCTION: The fault was during an instruction fetch.
438		− * @FAULT_FLAG_INTERRUPTIBLE: The fault can be interrupted by non-fatal signals.
439		− *
440		− * About @FAULT_FLAG_ALLOW_RETRY and @FAULT_FLAG_TRIED: we can specify
441		− * whether we would allow page faults to retry by specifying these two
442		− * fault flags correctly. Currently there can be three legal combinations:
443		− *
444		− * (a) ALLOW_RETRY and !TRIED: this means the page fault allows retry, and
445		− * this is the first try
446		− *
447		− * (b) ALLOW_RETRY and TRIED: this means the page fault allows retry, and
448		− * we've already tried at least once
449		− *
450		− * (c) !ALLOW_RETRY and !TRIED: this means the page fault does not allow retry
451		− *
452		− * The unlisted combination (!ALLOW_RETRY && TRIED) is illegal and should never
453		− * be used. Note that page faults can be allowed to retry for multiple times,
454		− * in which case we'll have an initial fault with flags (a) then later on
455		− * continuous faults with flags (b). We should always try to detect pending
456		− * signals before a retry to make sure the continuous page faults can still be
457		− * interrupted if necessary.
458		− */
459		−enum fault_flag {
460		− FAULT_FLAG_WRITE = 1 << 0,
461		− FAULT_FLAG_MKWRITE = 1 << 1,
462		− FAULT_FLAG_ALLOW_RETRY = 1 << 2,
463		− FAULT_FLAG_RETRY_NOWAIT = 1 << 3,
464		− FAULT_FLAG_KILLABLE = 1 << 4,
465		− FAULT_FLAG_TRIED = 1 << 5,
466		− FAULT_FLAG_USER = 1 << 6,
467		− FAULT_FLAG_REMOTE = 1 << 7,
468		− FAULT_FLAG_INSTRUCTION = 1 << 8,
469		− FAULT_FLAG_INTERRUPTIBLE = 1 << 9,
470		−};
471		−
472	427	/*
473	428	* The default fault flags that should be used by most of the
474	429	* arch-specific page fault handlers.

include/linux/mm_inline.h+86−0

@@ -2,6 +2,7 @@ · 1 unmodified line
2	2	#ifndef LINUX_MM_INLINE_H
3	3	#define LINUX_MM_INLINE_H
4	4
	5	+#include <linux/atomic.h>
5	6	#include <linux/huge_mm.h>
6	7	#include <linux/swap.h>
7	8	#include <linux/string.h>
@@ -185,4 +186,89 @@ static inline bool is_same_vma_anon_name(struct vm_area_struct *vma, · 177 unmodified lines
185	186	}
186	187	#endif /* CONFIG_ANON_VMA_NAME */
187	188
	189	+static inline void init_tlb_flush_pending(struct mm_struct *mm)
	190	+{
	191	+ atomic_set(&mm->tlb_flush_pending, 0);
	192	+}
	193	+
	194	+static inline void inc_tlb_flush_pending(struct mm_struct *mm)
	195	+{
	196	+ atomic_inc(&mm->tlb_flush_pending);
	197	+ /*
	198	+ * The only time this value is relevant is when there are indeed pages
	199	+ * to flush. And we'll only flush pages after changing them, which
	200	+ * requires the PTL.
	201	+ *
	202	+ * So the ordering here is:
	203	+ *
	204	+ * atomic_inc(&mm->tlb_flush_pending);
	205	+ * spin_lock(&ptl);
	206	+ * ...
	207	+ * set_pte_at();
	208	+ * spin_unlock(&ptl);
	209	+ *
	210	+ * spin_lock(&ptl)
	211	+ * mm_tlb_flush_pending();
	212	+ * ....
	213	+ * spin_unlock(&ptl);
	214	+ *
	215	+ * flush_tlb_range();
	216	+ * atomic_dec(&mm->tlb_flush_pending);
	217	+ *
	218	+ * Where the increment if constrained by the PTL unlock, it thus
	219	+ * ensures that the increment is visible if the PTE modification is
	220	+ * visible. After all, if there is no PTE modification, nobody cares
	221	+ * about TLB flushes either.
	222	+ *
	223	+ * This very much relies on users (mm_tlb_flush_pending() and
	224	+ * mm_tlb_flush_nested()) only caring about _specific_ PTEs (and
	225	+ * therefore specific PTLs), because with SPLIT_PTE_PTLOCKS and RCpc
	226	+ * locks (PPC) the unlock of one doesn't order against the lock of
	227	+ * another PTL.
	228	+ *
	229	+ * The decrement is ordered by the flush_tlb_range(), such that
	230	+ * mm_tlb_flush_pending() will not return false unless all flushes have
	231	+ * completed.
	232	+ */
	233	+}
	234	+
	235	+static inline void dec_tlb_flush_pending(struct mm_struct *mm)
	236	+{
	237	+ /*
	238	+ * See inc_tlb_flush_pending().
	239	+ *
	240	+ * This cannot be smp_mb__before_atomic() because smp_mb() simply does
	241	+ * not order against TLB invalidate completion, which is what we need.
	242	+ *
	243	+ * Therefore we must rely on tlb_flush_*() to guarantee order.
	244	+ */
	245	+ atomic_dec(&mm->tlb_flush_pending);
	246	+}
	247	+
	248	+static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
	249	+{
	250	+ /*
	251	+ * Must be called after having acquired the PTL; orders against that
	252	+ * PTLs release and therefore ensures that if we observe the modified
	253	+ * PTE we must also observe the increment from inc_tlb_flush_pending().
	254	+ *
	255	+ * That is, it only guarantees to return true if there is a flush
	256	+ * pending for _this_ PTL.
	257	+ */
	258	+ return atomic_read(&mm->tlb_flush_pending);
	259	+}
	260	+
	261	+static inline bool mm_tlb_flush_nested(struct mm_struct *mm)
	262	+{
	263	+ /*
	264	+ * Similar to mm_tlb_flush_pending(), we must have acquired the PTL
	265	+ * for which there is a TLB flush pending in order to guarantee
	266	+ * we've seen both that PTE modification and the increment.
	267	+ *
	268	+ * (no requirement on actually still holding the PTL, that is irrelevant)
	269	+ */
	270	+ return atomic_read(&mm->tlb_flush_pending) > 1;
	271	+}
	272	+
	273	+
188	274	#endif

include/linux/mm_types.h+45−84

@@ -692,90 +692,6 @@ extern void tlb_gather_mmu(struct mmu_gather tlb, struct mm_struct mm); · 691 unmodified lines
692	692	extern void tlb_gather_mmu_fullmm(struct mmu_gather tlb, struct mm_struct mm);
693	693	extern void tlb_finish_mmu(struct mmu_gather *tlb);
694	694
695		−static inline void init_tlb_flush_pending(struct mm_struct *mm)
696		−{
697		− atomic_set(&mm->tlb_flush_pending, 0);
698		−}
699		−
700		−static inline void inc_tlb_flush_pending(struct mm_struct *mm)
701		−{
702		− atomic_inc(&mm->tlb_flush_pending);
703		− /*
704		− * The only time this value is relevant is when there are indeed pages
705		− * to flush. And we'll only flush pages after changing them, which
706		− * requires the PTL.
707		− *
708		− * So the ordering here is:
709		− *
710		− * atomic_inc(&mm->tlb_flush_pending);
711		− * spin_lock(&ptl);
712		− * ...
713		− * set_pte_at();
714		− * spin_unlock(&ptl);
715		− *
716		− * spin_lock(&ptl)
717		− * mm_tlb_flush_pending();
718		− * ....
719		− * spin_unlock(&ptl);
720		− *
721		− * flush_tlb_range();
722		− * atomic_dec(&mm->tlb_flush_pending);
723		− *
724		− * Where the increment if constrained by the PTL unlock, it thus
725		− * ensures that the increment is visible if the PTE modification is
726		− * visible. After all, if there is no PTE modification, nobody cares
727		− * about TLB flushes either.
728		− *
729		− * This very much relies on users (mm_tlb_flush_pending() and
730		− * mm_tlb_flush_nested()) only caring about _specific_ PTEs (and
731		− * therefore specific PTLs), because with SPLIT_PTE_PTLOCKS and RCpc
732		− * locks (PPC) the unlock of one doesn't order against the lock of
733		− * another PTL.
734		− *
735		− * The decrement is ordered by the flush_tlb_range(), such that
736		− * mm_tlb_flush_pending() will not return false unless all flushes have
737		− * completed.
738		− */
739		−}
740		−
741		−static inline void dec_tlb_flush_pending(struct mm_struct *mm)
742		−{
743		− /*
744		− * See inc_tlb_flush_pending().
745		− *
746		− * This cannot be smp_mb__before_atomic() because smp_mb() simply does
747		− * not order against TLB invalidate completion, which is what we need.
748		− *
749		− * Therefore we must rely on tlb_flush_*() to guarantee order.
750		− */
751		− atomic_dec(&mm->tlb_flush_pending);
752		−}
753		−
754		−static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
755		−{
756		− /*
757		− * Must be called after having acquired the PTL; orders against that
758		− * PTLs release and therefore ensures that if we observe the modified
759		− * PTE we must also observe the increment from inc_tlb_flush_pending().
760		− *
761		− * That is, it only guarantees to return true if there is a flush
762		− * pending for _this_ PTL.
763		− */
764		− return atomic_read(&mm->tlb_flush_pending);
765		−}
766		−
767		−static inline bool mm_tlb_flush_nested(struct mm_struct *mm)
768		−{
769		− /*
770		− * Similar to mm_tlb_flush_pending(), we must have acquired the PTL
771		− * for which there is a TLB flush pending in order to guarantee
772		− * we've seen both that PTE modification and the increment.
773		− *
774		− * (no requirement on actually still holding the PTL, that is irrelevant)
775		− */
776		− return atomic_read(&mm->tlb_flush_pending) > 1;
777		−}
778		−
779	695	struct vm_fault;
780	696
781	697	/**
@@ -890,4 +806,49 @@ typedef struct { · 108 unmodified lines
890	806	unsigned long val;
891	807	} swp_entry_t;
892	808
	809	+/**
	810	+ * enum fault_flag - Fault flag definitions.
	811	+ * @FAULT_FLAG_WRITE: Fault was a write fault.
	812	+ * @FAULT_FLAG_MKWRITE: Fault was mkwrite of existing PTE.
	813	+ * @FAULT_FLAG_ALLOW_RETRY: Allow to retry the fault if blocked.
	814	+ * @FAULT_FLAG_RETRY_NOWAIT: Don't drop mmap_lock and wait when retrying.
	815	+ * @FAULT_FLAG_KILLABLE: The fault task is in SIGKILL killable region.
	816	+ * @FAULT_FLAG_TRIED: The fault has been tried once.
	817	+ * @FAULT_FLAG_USER: The fault originated in userspace.
	818	+ * @FAULT_FLAG_REMOTE: The fault is not for current task/mm.
	819	+ * @FAULT_FLAG_INSTRUCTION: The fault was during an instruction fetch.
	820	+ * @FAULT_FLAG_INTERRUPTIBLE: The fault can be interrupted by non-fatal signals.
	821	+ *
	822	+ * About @FAULT_FLAG_ALLOW_RETRY and @FAULT_FLAG_TRIED: we can specify
	823	+ * whether we would allow page faults to retry by specifying these two
	824	+ * fault flags correctly. Currently there can be three legal combinations:
	825	+ *
	826	+ * (a) ALLOW_RETRY and !TRIED: this means the page fault allows retry, and
	827	+ * this is the first try
	828	+ *
	829	+ * (b) ALLOW_RETRY and TRIED: this means the page fault allows retry, and
	830	+ * we've already tried at least once
	831	+ *
	832	+ * (c) !ALLOW_RETRY and !TRIED: this means the page fault does not allow retry
	833	+ *
	834	+ * The unlisted combination (!ALLOW_RETRY && TRIED) is illegal and should never
	835	+ * be used. Note that page faults can be allowed to retry for multiple times,
	836	+ * in which case we'll have an initial fault with flags (a) then later on
	837	+ * continuous faults with flags (b). We should always try to detect pending
	838	+ * signals before a retry to make sure the continuous page faults can still be
	839	+ * interrupted if necessary.
	840	+ */
	841	+enum fault_flag {
	842	+ FAULT_FLAG_WRITE = 1 << 0,
	843	+ FAULT_FLAG_MKWRITE = 1 << 1,
	844	+ FAULT_FLAG_ALLOW_RETRY = 1 << 2,
	845	+ FAULT_FLAG_RETRY_NOWAIT = 1 << 3,
	846	+ FAULT_FLAG_KILLABLE = 1 << 4,
	847	+ FAULT_FLAG_TRIED = 1 << 5,
	848	+ FAULT_FLAG_USER = 1 << 6,
	849	+ FAULT_FLAG_REMOTE = 1 << 7,
	850	+ FAULT_FLAG_INSTRUCTION = 1 << 8,
	851	+ FAULT_FLAG_INTERRUPTIBLE = 1 << 9,
	852	+};
	853	+
893	854	#endif /* _LINUX_MM_TYPES_H */

mm: move tlb_flush_pending inline helpers to mm_inline.h

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