linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: Liam Howlett <liam.howlett@oracle.com>
To: "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Song Liu <songliubraving@fb.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Matthew Wilcox <willy@infradead.org>,
	Laurent Dufour <ldufour@linux.ibm.com>,
	David Rientjes <rientjes@google.com>,
	Axel Rasmussen <axelrasmussen@google.com>,
	Suren Baghdasaryan <surenb@google.com>,
	Vlastimil Babka <vbabka@suse.cz>, Rik van Riel <riel@surriel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Michel Lespinasse <walken.cr@gmail.com>,
	Liam Howlett <liam.howlett@oracle.com>
Subject: [PATCH 45/94] mm/mmap: Change __do_munmap() to avoid unnecessary lookups.
Date: Wed, 28 Apr 2021 15:36:11 +0000	[thread overview]
Message-ID: <20210428153542.2814175-46-Liam.Howlett@Oracle.com> (raw)
In-Reply-To: <20210428153542.2814175-1-Liam.Howlett@Oracle.com>

As there is no longer a vmacache, find_vma() is more expensive and so
avoid doing them

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---
 mm/mmap.c | 115 ++++++++++++++++++++++++++++--------------------------
 1 file changed, 59 insertions(+), 56 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 10c42a41e023..8ce36776fe43 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2551,44 +2551,6 @@ static void unmap_region(struct mm_struct *mm,
 	tlb_finish_mmu(&tlb);
 }
 
-/*
- * Create a list of vma's touched by the unmap, removing them from the mm's
- * vma list as we go..
- */
-static bool
-detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
-	struct vm_area_struct *prev, unsigned long end)
-{
-	struct vm_area_struct **insertion_point;
-	struct vm_area_struct *tail_vma = NULL;
-
-	insertion_point = (prev ? &prev->vm_next : &mm->mmap);
-	vma->vm_prev = NULL;
-	vma_mt_szero(mm, vma->vm_start, end);
-	do {
-		mm->map_count--;
-		tail_vma = vma;
-		vma = vma->vm_next;
-	} while (vma && vma->vm_start < end);
-	*insertion_point = vma;
-	if (vma)
-		vma->vm_prev = prev;
-	else
-		mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
-	tail_vma->vm_next = NULL;
-
-	/*
-	 * Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or
-	 * VM_GROWSUP VMA. Such VMAs can change their size under
-	 * down_read(mmap_lock) and collide with the VMA we are about to unmap.
-	 */
-	if (vma && (vma->vm_flags & VM_GROWSDOWN))
-		return false;
-	if (prev && (prev->vm_flags & VM_GROWSUP))
-		return false;
-	return true;
-}
-
 /*
  * __split_vma() bypasses sysctl_max_map_count checking.  We use this where it
  * has already been checked or doesn't make sense to fail.
@@ -2668,18 +2630,24 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
 	return __split_vma(mm, vma, addr, new_below);
 }
 
-static inline void unlock_range(struct vm_area_struct *start, unsigned long limit)
+static inline int unlock_range(struct vm_area_struct *start,
+			       struct vm_area_struct **tail, unsigned long limit)
 {
 	struct mm_struct *mm = start->vm_mm;
 	struct vm_area_struct *tmp = start;
+	int count = 0;
 
 	while (tmp && tmp->vm_start < limit) {
+		*tail = tmp;
+		count++;
 		if (tmp->vm_flags & VM_LOCKED) {
 			mm->locked_vm -= vma_pages(tmp);
 			munlock_vma_pages_all(tmp);
 		}
 		tmp = tmp->vm_next;
 	}
+
+	return count;
 }
 /* Munmap is split into 2 main parts -- this part which finds
  * what needs doing, and the areas themselves, which do the
@@ -2691,24 +2659,24 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
 {
 	unsigned long end;
 	struct vm_area_struct *vma, *prev, *last;
+	MA_STATE(mas, &mm->mm_mt, start, start);
 
 	if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
 		return -EINVAL;
 
-	len = PAGE_ALIGN(len);
-	end = start + len;
-	if (len == 0)
+	end = start + PAGE_ALIGN(len);
+	if (end == start)
 		return -EINVAL;
 
 	 /* arch_unmap() might do unmaps itself.  */
 	arch_unmap(mm, start, end);
 
 	/* Find the first overlapping VMA */
-	vma = find_vma_intersection(mm, start, end);
+	vma = mas_find(&mas, end - 1);
 	if (!vma)
 		return 0;
 
-	prev = vma->vm_prev;
+	mas.last = end - 1;
 	/* we have start < vma->vm_end  */
 
 	/*
@@ -2732,16 +2700,27 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
 		if (error)
 			return error;
 		prev = vma;
+		vma = vma_next(mm, prev);
+		mas.index = start;
+		mas_reset(&mas);
+	} else {
+		prev = vma->vm_prev;
 	}
 
+	if (vma->vm_end >= end)
+		last = vma;
+	else
+		last = find_vma_intersection(mm, end - 1, end);
+
 	/* Does it split the last one? */
-	last = find_vma(mm, end);
-	if (last && end > last->vm_start) {
+	if (last && end < last->vm_end) {
 		int error = __split_vma(mm, last, end, 1);
 		if (error)
 			return error;
+		vma = vma_next(mm, prev);
+		mas_reset(&mas);
 	}
-	vma = vma_next(mm, prev);
+
 
 	if (unlikely(uf)) {
 		/*
@@ -2754,22 +2733,46 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
 		 * failure that it's not worth optimizing it for.
 		 */
 		int error = userfaultfd_unmap_prep(vma, start, end, uf);
+
 		if (error)
 			return error;
 	}
 
 	/*
-	 * unlock any mlock()ed ranges before detaching vmas
+	 * unlock any mlock()ed ranges before detaching vmas, count the number
+	 * of VMAs to be dropped, and return the tail entry of the affected
+	 * area.
 	 */
-	if (mm->locked_vm)
-		unlock_range(vma, end);
+	mm->map_count -= unlock_range(vma, &last, end);
+	/* Drop removed area from the tree */
+	mas_store_gfp(&mas, NULL, GFP_KERNEL);
+
+	/* Detach vmas from the MM linked list */
+	vma->vm_prev = NULL;
+	if (prev)
+		prev->vm_next = last->vm_next;
+	else
+		mm->mmap = last->vm_next;
 
-	/* Detach vmas from the MM linked list and remove from the mm tree*/
-	if (!detach_vmas_to_be_unmapped(mm, vma, prev, end))
-		downgrade = false;
+	if (last->vm_next) {
+		last->vm_next->vm_prev = prev;
+		last->vm_next = NULL;
+	} else
+		mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
 
-	if (downgrade)
-		mmap_write_downgrade(mm);
+	/*
+	 * Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or
+	 * VM_GROWSUP VMA. Such VMAs can change their size under
+	 * down_read(mmap_lock) and collide with the VMA we are about to unmap.
+	 */
+	if (downgrade) {
+		if (last && (last->vm_flags & VM_GROWSDOWN))
+			downgrade = false;
+		else if (prev && (prev->vm_flags & VM_GROWSUP))
+			downgrade = false;
+		else
+			mmap_write_downgrade(mm);
+	}
 
 	unmap_region(mm, vma, prev, start, end);
 
@@ -3182,7 +3185,7 @@ void exit_mmap(struct mm_struct *mm)
 	}
 
 	if (mm->locked_vm)
-		unlock_range(mm->mmap, ULONG_MAX);
+		unlock_range(mm->mmap, &vma, ULONG_MAX);
 
 	arch_exit_mmap(mm);
 
-- 
2.30.2


  parent reply	other threads:[~2021-04-28 15:37 UTC|newest]

Thread overview: 137+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-28 15:35 [PATCH 00/94] Introducing the Maple Tree Liam Howlett
2021-04-28 15:35 ` [PATCH 01/94] mm: Add vma_lookup() Liam Howlett
2021-05-01  5:04   ` Michel Lespinasse
2021-05-03 16:08     ` Liam Howlett
2021-04-28 15:35 ` [PATCH 02/94] drm/i915/selftests: Use vma_lookup() in __igt_mmap() Liam Howlett
2021-04-28 15:35 ` [PATCH 03/94] arch/arc/kernel/troubleshoot: use vma_lookup() instead of find_vma_intersection() Liam Howlett
2021-04-28 15:35 ` [PATCH 04/94] arch/arm64/kvm: Use " Liam Howlett
2021-04-28 15:35 ` [PATCH 05/94] arch/powerpc/kvm/book3s_hv_uvmem: " Liam Howlett
2021-04-28 15:35 ` [PATCH 06/94] arch/powerpc/kvm/book3s: Use vma_lookup() in kvmppc_hv_setup_htab_rma() Liam Howlett
2021-04-28 15:35 ` [PATCH 08/94] x86/sgx: Use vma_lookup() in sgx_encl_find() Liam Howlett
2021-04-28 15:35 ` [PATCH 07/94] arch/mips/kernel/traps: Use vma_lookup() instead of find_vma_intersection() Liam Howlett
2021-04-28 15:35 ` [PATCH 09/94] virt/kvm: " Liam Howlett
2021-04-28 15:35 ` [PATCH 10/94] vfio: " Liam Howlett
2021-04-28 15:35 ` [PATCH 12/94] drm/amdgpu: Use vma_lookup() in amdgpu_ttm_tt_get_user_pages() Liam Howlett
2021-04-28 15:35 ` [PATCH 11/94] net/ipv5/tcp: Use vma_lookup() in tcp_zerocopy_receive() Liam Howlett
2021-04-28 15:35 ` [PATCH 15/94] kernel/events/uprobes: Use vma_lookup() in find_active_uprobe() Liam Howlett
2021-04-28 15:35 ` [PATCH 14/94] misc/sgi-gru/grufault: Use vma_lookup() in gru_find_vma() Liam Howlett
2021-04-28 15:35 ` [PATCH 13/94] media: videobuf2: Use vma_lookup() in get_vaddr_frames() Liam Howlett
2021-04-28 15:35 ` [PATCH 16/94] lib/test_hmm: Use vma_lookup() in dmirror_migrate() Liam Howlett
2021-04-28 15:35 ` [PATCH 18/94] mm/migrate: Use vma_lookup() in do_pages_stat_array() Liam Howlett
2021-04-28 15:35 ` [PATCH 17/94] mm/ksm: Use vma_lookup() in find_mergeable_vma() Liam Howlett
2021-04-28 15:35 ` [PATCH 19/94] mm/mremap: Use vma_lookup() in vma_to_resize() Liam Howlett
2021-04-28 15:35 ` [PATCH 20/94] mm/memory.c: Use vma_lookup() instead of find_vma_intersection() Liam Howlett
2021-04-28 15:35 ` [PATCH 21/94] radix tree test suite: Enhancements for Maple Tree Liam Howlett
2021-05-28 17:30   ` Suren Baghdasaryan
2021-05-28 18:54     ` Liam Howlett
2021-04-28 15:35 ` [PATCH 23/94] radix tree test suite: Add support for kmem_cache_free_bulk Liam Howlett
2021-05-28 17:55   ` Suren Baghdasaryan
2021-05-28 19:07     ` Liam Howlett
2021-04-28 15:35 ` [PATCH 22/94] radix tree test suite: Add support for fallthrough attribute Liam Howlett
2021-04-28 15:35 ` [PATCH 24/94] radix tree test suite: Add keme_cache_alloc_bulk() support Liam Howlett
2021-05-28 18:17   ` Suren Baghdasaryan
2021-05-28 19:28     ` Liam Howlett
2021-04-28 15:35 ` [PATCH 25/94] radix tree test suite: Add __must_be_array() support Liam Howlett
2021-04-28 15:36 ` [PATCH 26/94] Maple Tree: Add new data structure Liam Howlett
2021-05-14 10:40   ` Peter Zijlstra
2021-05-14 20:36     ` Liam Howlett
2021-05-14 10:56   ` Peter Zijlstra
2021-05-14 20:45     ` Liam Howlett
2021-05-14 11:13   ` Peter Zijlstra
2021-05-14 11:27     ` Peter Zijlstra
2021-05-14 21:23       ` Liam Howlett
2021-05-14 11:20   ` Peter Zijlstra
2021-05-14 20:46     ` Liam Howlett
2021-05-14 11:54   ` Peter Zijlstra
2021-05-14 21:25     ` Liam Howlett
2021-05-14 12:17   ` Peter Zijlstra
2021-05-14 12:43     ` Matthew Wilcox
2021-05-14 21:29     ` Liam Howlett
2021-05-14 13:42   ` Peter Zijlstra
2021-05-14 21:42     ` Liam Howlett
2021-05-14 15:32   ` Peter Zijlstra
2021-05-14 15:34     ` Peter Zijlstra
2021-05-14 21:57       ` Liam Howlett
2021-05-14 21:43     ` Liam Howlett
2021-05-14 15:40   ` Peter Zijlstra
2021-05-15  0:02     ` Liam Howlett
2021-04-28 15:36 ` [PATCH 28/94] mm/mmap: Introduce unlock_range() for code cleanup Liam Howlett
2021-04-28 15:36 ` [PATCH 27/94] mm: Start tracking VMAs with maple tree Liam Howlett
2021-04-28 15:36 ` [PATCH 30/94] mm/mmap: Change find_vma_prev() to use " Liam Howlett
2021-04-28 15:36 ` [PATCH 29/94] mm/mmap: Change find_vma() to use the " Liam Howlett
2021-04-28 15:36 ` [PATCH 32/94] kernel/fork: Convert dup_mmap to use " Liam Howlett
2021-05-29  0:42   ` Suren Baghdasaryan
2021-05-31 13:39     ` Liam Howlett
2021-04-28 15:36 ` [PATCH 31/94] mm/mmap: Change unmapped_area and unmapped_area_topdown " Liam Howlett
2021-04-28 15:36 ` [PATCH 33/94] mm: Remove rb tree Liam Howlett
2021-05-29  1:26   ` Suren Baghdasaryan
2021-05-31 13:42     ` Liam Howlett
2021-04-28 15:36 ` [PATCH 35/94] xen/privcmd: Optimized privcmd_ioctl_mmap() by using vma_lookup() Liam Howlett
2021-04-28 15:36 ` [PATCH 34/94] arch/m68k/kernel/sys_m68k: Use vma_lookup() in sys_cacheflush() Liam Howlett
2021-04-28 15:36 ` [PATCH 37/94] mm/khugepaged: Optimize collapse_pte_mapped_thp() by using vma_lookup() Liam Howlett
2021-04-28 15:36 ` [PATCH 36/94] mm: Optimize find_exact_vma() to use vma_lookup() Liam Howlett
2021-04-28 15:36 ` [PATCH 38/94] mm/gup: Add mm_populate_vma() for use when the vma is known Liam Howlett
2021-05-01  5:13   ` Michel Lespinasse
2021-05-03 15:53     ` Liam Howlett
2021-05-03 16:00       ` Matthew Wilcox
2021-05-03 23:01         ` Liam Howlett
2021-04-28 15:36 ` [PATCH 39/94] mm/mmap: Change do_brk_flags() to expand existing VMA and add do_brk_munmap() Liam Howlett
2021-04-28 15:36 ` [PATCH 40/94] mm/mmap: Change vm_brk_flags() to use mm_populate_vma() Liam Howlett
2021-04-28 15:36 ` [PATCH 41/94] mm: Change find_vma_intersection() to maple tree and make find_vma() to inline Liam Howlett
2021-04-28 15:36 ` [PATCH 44/94] mm: Remove vmacache Liam Howlett
2021-04-28 15:36 ` [PATCH 43/94] mm/mmap: Drop munmap_vma_range() Liam Howlett
2021-04-28 15:36 ` [PATCH 42/94] mm/mmap: Change mmap_region() to use maple tree state Liam Howlett
2021-04-28 15:36 ` Liam Howlett [this message]
2021-04-28 15:36 ` [PATCH 46/94] mm/mmap: Move mmap_region() below do_munmap() Liam Howlett
2021-04-28 15:36 ` [PATCH 47/94] mm/mmap: Add do_mas_munmap() and wraper for __do_munmap() Liam Howlett
2021-04-28 15:36 ` [PATCH 48/94] mmap: Use find_vma_intersection in do_mmap() for overlap Liam Howlett
2021-04-28 15:36 ` [PATCH 49/94] mmap: Remove __do_munmap() in favour of do_mas_munmap() Liam Howlett
2021-04-28 15:36 ` [PATCH 50/94] mm/mmap: Change do_brk_munmap() to use do_mas_align_munmap() Liam Howlett
2021-04-28 15:36 ` [PATCH 51/94] mmap: make remove_vma_list() inline Liam Howlett
2021-04-28 15:36 ` [PATCH 52/94] mm: Introduce vma_next() and vma_prev() Liam Howlett
2021-04-28 15:36 ` [PATCH 53/94] arch/arm64: Remove mmap linked list from vdso Liam Howlett
2021-04-28 15:36 ` [PATCH 54/94] arch/parisc: Remove mmap linked list from kernel/cache Liam Howlett
2021-04-28 15:36 ` [PATCH 55/94] arch/powerpc: Remove mmap linked list from mm/book3s32/tlb Liam Howlett
2021-04-28 15:36 ` [PATCH 56/94] arch/powerpc: Remove mmap linked list from mm/book3s64/subpage_prot Liam Howlett
2021-04-28 15:36 ` [PATCH 57/94] arch/s390: Use maple tree iterators instead of linked list Liam Howlett
2021-04-28 15:36 ` [PATCH 58/94] arch/x86: Use maple tree iterators for vdso/vma Liam Howlett
2021-04-28 15:36 ` [PATCH 59/94] arch/xtensa: Use maple tree iterators for unmapped area Liam Howlett
2021-04-28 15:36 ` [PATCH 60/94] drivers/misc/cxl: Use maple tree iterators for cxl_prefault_vma() Liam Howlett
2021-04-28 15:36 ` [PATCH 61/94] drivers/tee/optee: Use maple tree iterators for __check_mem_type() Liam Howlett
2021-04-28 15:36 ` [PATCH 63/94] fs/coredump: Use maple tree iterators in place of linked list Liam Howlett
2021-04-28 15:36 ` [PATCH 62/94] fs/binfmt_elf: Use maple tree iterators for fill_files_note() Liam Howlett
2021-04-28 15:36 ` [PATCH 64/94] fs/exec: Use vma_next() instead of linked list Liam Howlett
2021-04-28 15:36 ` [PATCH 65/94] fs/proc/base: Use maple tree iterators in place " Liam Howlett
2021-04-28 15:36 ` [PATCH 66/94] fs/proc/task_mmu: Stop using linked list and highest_vm_end Liam Howlett
2021-04-28 15:36 ` [PATCH 67/94] fs/userfaultfd: Stop using vma linked list Liam Howlett
2021-04-28 15:36 ` [PATCH 68/94] ipc/shm: Stop using the " Liam Howlett
2021-04-28 15:36 ` [PATCH 69/94] kernel/acct: Use maple tree iterators instead of " Liam Howlett
2021-04-28 15:36 ` [PATCH 70/94] kernel/events/core: " Liam Howlett
2021-04-28 15:36 ` [PATCH 71/94] kernel/events/uprobes: " Liam Howlett
2021-04-28 15:36 ` [PATCH 73/94] kernel/sys: " Liam Howlett
2021-04-28 15:36 ` [PATCH 72/94] kernel/sched/fair: " Liam Howlett
2021-04-28 15:36 ` [PATCH 75/94] mm/huge_memory: Use vma_next() instead of vma " Liam Howlett
2021-04-28 15:36 ` [PATCH 76/94] mm/khugepaged: Use maple tree iterators " Liam Howlett
2021-05-04  4:29   ` [PATCH 76/94] mm/khugepaged: Use maple tree iterators instead of vma Hillf Danton
2021-05-04 14:05     ` Liam Howlett
2021-04-28 15:36 ` [PATCH 74/94] mm/gup: Use maple tree navigation instead of linked list Liam Howlett
2021-04-28 15:36 ` [PATCH 77/94] mm/ksm: Use maple tree iterators instead of vma " Liam Howlett
2021-04-28 15:36 ` [PATCH 78/94] mm/madvise: Use vma_next " Liam Howlett
2021-04-28 15:36 ` [PATCH 79/94] mm/memcontrol: Stop using mm->highest_vm_end Liam Howlett
2021-04-28 15:36 ` [PATCH 81/94] mm/mlock: Use maple tree iterators instead of vma linked list Liam Howlett
2021-04-28 15:36 ` [PATCH 80/94] mm/mempolicy: " Liam Howlett
2021-04-28 15:36 ` [PATCH 82/94] mm/mprotect: Use maple tree navigation " Liam Howlett
2021-04-28 15:36 ` [PATCH 84/94] mm/msync: Use vma_next() " Liam Howlett
2021-04-28 15:36 ` [PATCH 83/94] mm/mremap: " Liam Howlett
2021-04-28 15:36 ` [PATCH 86/94] mm/pagewalk: " Liam Howlett
2021-04-28 15:36 ` [PATCH 85/94] mm/oom_kill: Use maple tree iterators " Liam Howlett
2021-04-28 15:36 ` [PATCH 87/94] mm/swapfile: Use maple tree iterator " Liam Howlett
2021-04-28 15:36 ` [PATCH 88/94] mm/util: Remove __vma_link_list() and __vma_unlink_list() Liam Howlett
2021-04-28 15:36 ` [PATCH 89/94] arch/um/kernel/tlb: Stop using linked list Liam Howlett
2021-04-28 15:36 ` [PATCH 90/94] bpf: Remove VMA " Liam Howlett
2021-04-28 15:36 ` [PATCH 91/94] mm: Remove vma " Liam Howlett
2021-04-28 15:36 ` [PATCH 92/94] mm: Return a bool from anon_vma_interval_tree_verify() Liam Howlett
2021-04-28 15:36 ` [PATCH 94/94] mm: Move mas locking outside of munmap() path Liam Howlett
2021-05-01  6:13   ` Michel Lespinasse
2021-05-03 16:05     ` Liam Howlett
2021-04-28 15:36 ` [PATCH 93/94] mm/mmap: Add mas_split_vma() and use it for munmap() Liam Howlett

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210428153542.2814175-46-Liam.Howlett@Oracle.com \
    --to=liam.howlett@oracle.com \
    --cc=akpm@linux-foundation.org \
    --cc=axelrasmussen@google.com \
    --cc=dave@stgolabs.net \
    --cc=ldufour@linux.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=maple-tree@lists.infradead.org \
    --cc=paulmck@kernel.org \
    --cc=peterz@infradead.org \
    --cc=riel@surriel.com \
    --cc=rientjes@google.com \
    --cc=songliubraving@fb.com \
    --cc=surenb@google.com \
    --cc=vbabka@suse.cz \
    --cc=walken.cr@gmail.com \
    --cc=willy@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).