[PATCH 1/2] Revert "io_uring/memmap: account the pages a compound region really uses"

[Jens Axboe <axboe@kernel.dk>]

This reverts commit f12f0234cc14886bcfd53ffb7c8df4216dad51f1.

The next patch stops charging kernel allocated regions to RLIMIT_MEMLOCK
altogether, which leaves nothing for this to account. Revert it first so
that fix applies cleanly to the stable trees that need it, none of which
have this commit.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/memmap.c | 37 +++++++------------------------------
 1 file changed, 7 insertions(+), 30 deletions(-)

diff --git a/io_uring/memmap.c b/io_uring/memmap.c
index 48c0eb012412..23e8a85111bc 100644
--- a/io_uring/memmap.c
+++ b/io_uring/memmap.c
@@ -16,10 +16,8 @@
 #include "zcrx.h"
 
 static bool io_mem_alloc_compound(struct page **pages, int nr_pages,
-				  size_t size, gfp_t gfp,
-				  struct user_struct *user)
+				  size_t size, gfp_t gfp)
 {
-	unsigned long nr_compound, extra;
 	struct page *page;
 	int i, order;
 
@@ -29,22 +27,9 @@ static bool io_mem_alloc_compound(struct page **pages, int nr_pages,
 	else if (order)
 		gfp |= __GFP_COMP;
 
-	/*
-	 * get_order() rounds a non power of two size up, so the allocation
-	 * can hold more pages than the region exposes. Account those too,
-	 * and leave the compound allocation alone if they do not fit.
-	 */
-	nr_compound = 1UL << order;
-	extra = nr_compound - nr_pages;
-	if (extra && user && __io_account_mem(user, extra))
-		return false;
-
 	page = alloc_pages(gfp, order);
-	if (!page) {
-		if (extra && user)
-			__io_unaccount_mem(user, extra);
+	if (!page)
 		return false;
-	}
 
 	for (i = 0; i < nr_pages; i++)
 		pages[i] = page + i;
@@ -120,15 +105,8 @@ void io_free_region(struct user_struct *user, struct io_mapped_region *mr)
 	}
 	if ((mr->flags & IO_REGION_F_VMAP) && mr->ptr)
 		vunmap(mr->ptr);
-	if (mr->nr_pages && user) {
-		unsigned long nr_accounted = mr->nr_pages;
-
-		/* a compound region was accounted for the whole allocation */
-		if (mr->flags & IO_REGION_F_SINGLE_REF)
-			nr_accounted = 1UL << get_order(io_region_size(mr));
-
-		__io_unaccount_mem(user, nr_accounted);
-	}
+	if (mr->nr_pages && user)
+		__io_unaccount_mem(user, mr->nr_pages);
 
 	memset(mr, 0, sizeof(*mr));
 }
@@ -173,8 +151,7 @@ static int io_region_pin_pages(struct io_mapped_region *mr,
 
 static int io_region_allocate_pages(struct io_mapped_region *mr,
 				    struct io_uring_region_desc *reg,
-				    unsigned long mmap_offset,
-				    struct user_struct *user)
+				    unsigned long mmap_offset)
 {
 	gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN;
 	size_t size = io_region_size(mr);
@@ -185,7 +162,7 @@ static int io_region_allocate_pages(struct io_mapped_region *mr,
 	if (!pages)
 		return -ENOMEM;
 
-	if (io_mem_alloc_compound(pages, mr->nr_pages, size, gfp, user)) {
+	if (io_mem_alloc_compound(pages, mr->nr_pages, size, gfp)) {
 		mr->flags |= IO_REGION_F_SINGLE_REF;
 		goto done;
 	}
@@ -240,7 +217,7 @@ int io_create_region(struct io_ring_ctx *ctx, struct io_mapped_region *mr,
 	if (reg->flags & IORING_MEM_REGION_TYPE_USER)
 		ret = io_region_pin_pages(mr, reg);
 	else
-		ret = io_region_allocate_pages(mr, reg, mmap_offset, ctx->user);
+		ret = io_region_allocate_pages(mr, reg, mmap_offset);
 	if (ret)
 		goto out_free;
 
-- 
2.55.0