[PATCH AUTOSEL 5.10 32/51] io_uring: drop file refs after task cancel

[PATCH AUTOSEL 5.10 32/51] io_uring: drop file refs after task cancel

[Sasha Levin]

From: Pavel Begunkov <asml.silence@gmail.com>

[ Upstream commit de7f1d9e99d8b99e4e494ad8fcd91f0c4c5c9357 ]

io_uring fds marked O_CLOEXEC and we explicitly cancel all requests
before going through exec, so we don't want to leave task's file
references to not our anymore io_uring instances.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/io_uring.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1f798c5c4213e..aebdbc842a637 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8807,6 +8807,15 @@ static void io_uring_attempt_task_drop(struct file *file)
 		io_uring_del_task_file(file);
 }
 
+static void io_uring_remove_task_files(struct io_uring_task *tctx)
+{
+	struct file *file;
+	unsigned long index;
+
+	xa_for_each(&tctx->xa, index, file)
+		io_uring_del_task_file(file);
+}
+
 void __io_uring_files_cancel(struct files_struct *files)
 {
 	struct io_uring_task *tctx = current->io_uring;
@@ -8815,16 +8824,12 @@ void __io_uring_files_cancel(struct files_struct *files)
 
 	/* make sure overflow events are dropped */
 	atomic_inc(&tctx->in_idle);
-
-	xa_for_each(&tctx->xa, index, file) {
-		struct io_ring_ctx *ctx = file->private_data;
-
-		io_uring_cancel_task_requests(ctx, files);
-		if (files)
-			io_uring_del_task_file(file);
-	}
-
+	xa_for_each(&tctx->xa, index, file)
+		io_uring_cancel_task_requests(file->private_data, files);
 	atomic_dec(&tctx->in_idle);
+
+	if (files)
+		io_uring_remove_task_files(tctx);
 }
 
 static s64 tctx_inflight(struct io_uring_task *tctx)
@@ -8887,6 +8892,8 @@ void __io_uring_task_cancel(void)
 
 	finish_wait(&tctx->wait, &wait);
 	atomic_dec(&tctx->in_idle);
+
+	io_uring_remove_task_files(tctx);
 }
 
 static int io_uring_flush(struct file *file, void *data)
-- 
2.27.0

[PATCH AUTOSEL 5.10 34/51] arch/arc: add copy_user_page() to <asm/page.h> to fix build error on ARC

[Sasha Levin]

From: Randy Dunlap <rdunlap@infradead.org>

[ Upstream commit 8a48c0a3360bf2bf4f40c980d0ec216e770e58ee ]

fs/dax.c uses copy_user_page() but ARC does not provide that interface,
resulting in a build error.

Provide copy_user_page() in <asm/page.h>.

../fs/dax.c: In function 'copy_cow_page_dax':
../fs/dax.c:702:2: error: implicit declaration of function 'copy_user_page'; did you mean 'copy_to_user_page'? [-Werror=implicit-function-declaration]

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: linux-snps-arc@lists.infradead.org
Cc: Dan Williams <dan.j.williams@intel.com>
#Acked-by: Vineet Gupta <vgupta@synopsys.com> # v1
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
#Reviewed-by: Ira Weiny <ira.weiny@intel.com> # v2
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/arc/include/asm/page.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arc/include/asm/page.h b/arch/arc/include/asm/page.h
index b0dfed0f12be0..d9c264dc25fcb 100644
--- a/arch/arc/include/asm/page.h
+++ b/arch/arc/include/asm/page.h
@@ -10,6 +10,7 @@
 #ifndef __ASSEMBLY__
 
 #define clear_page(paddr)		memset((paddr), 0, PAGE_SIZE)
+#define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 #define copy_page(to, from)		memcpy((to), (from), PAGE_SIZE)
 
 struct vm_area_struct;
-- 
2.27.0

[PATCH AUTOSEL 5.10 51/51] poll: fix performance regression due to out-of-line __put_user()

[Sasha Levin]

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit ef0ba05538299f1391cbe097de36895bb36ecfe6 ]

The kernel test robot reported a -5.8% performance regression on the
"poll2" test of will-it-scale, and bisected it to commit d55564cfc222
("x86: Make __put_user() generate an out-of-line call").

I didn't expect an out-of-line __put_user() to matter, because no normal
core code should use that non-checking legacy version of user access any
more.  But I had overlooked the very odd poll() usage, which does a
__put_user() to update the 'revents' values of the poll array.

Now, Al Viro correctly points out that instead of updating just the
'revents' field, it would be much simpler to just copy the _whole_
pollfd entry, and then we could just use "copy_to_user()" on the whole
array of entries, the same way we use "copy_from_user()" a few lines
earlier to get the original values.

But that is not what we've traditionally done, and I worry that threaded
applications might be concurrently modifying the other fields of the
pollfd array.  So while Al's suggestion is simpler - and perhaps worth
trying in the future - this instead keeps the "just update revents"
model.

To fix the performance regression, use the modern "unsafe_put_user()"
instead of __put_user(), with the proper "user_write_access_begin()"
guarding in place. This improves code generation enormously.

Link: https://lore.kernel.org/lkml/20210107134723.GA28532@xsang-OptiPlex-9020/
Reported-by: kernel test robot <oliver.sang@intel.com>
Tested-by: Oliver Sang <oliver.sang@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: David Laight <David.Laight@aculab.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/select.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/fs/select.c b/fs/select.c
index ebfebdfe5c69a..37aaa8317f3ae 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -1011,14 +1011,17 @@ static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
 	fdcount = do_poll(head, &table, end_time);
 	poll_freewait(&table);
 
+	if (!user_write_access_begin(ufds, nfds * sizeof(*ufds)))
+		goto out_fds;
+
 	for (walk = head; walk; walk = walk->next) {
 		struct pollfd *fds = walk->entries;
 		int j;
 
-		for (j = 0; j < walk->len; j++, ufds++)
-			if (__put_user(fds[j].revents, &ufds->revents))
-				goto out_fds;
+		for (j = walk->len; j; fds++, ufds++, j--)
+			unsafe_put_user(fds->revents, &ufds->revents, Efault);
   	}
+	user_write_access_end();
 
 	err = fdcount;
 out_fds:
@@ -1030,6 +1033,11 @@ static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
 	}
 
 	return err;
+
+Efault:
+	user_write_access_end();
+	err = -EFAULT;
+	goto out_fds;
 }
 
 static long do_restart_poll(struct restart_block *restart_block)
-- 
2.27.0