Date:   Sat,  9 Jan 2021 16:26:45 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        torvalds@...ux-foundation.org, stable@...r.kernel.org
Cc:     lwn@....net, jslaby@...e.cz,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: Linux 5.4.88

diff --git a/Makefile b/Makefile
index 71968b4bb313..450ebe152806 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 VERSION = 5
 PATCHLEVEL = 4
-SUBLEVEL = 87
+SUBLEVEL = 88
 EXTRAVERSION =
 NAME = Kleptomaniac Octopus
 
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index ff366c2f58c1..303bc3e601a1 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -1673,9 +1673,11 @@ static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);
 
-	atslave = kzalloc(sizeof(*atslave), GFP_KERNEL);
-	if (!atslave)
+	atslave = kmalloc(sizeof(*atslave), GFP_KERNEL);
+	if (!atslave) {
+		put_device(&dmac_pdev->dev);
 		return NULL;
+	}
 
 	atslave->cfg = ATC_DST_H2SEL_HW | ATC_SRC_H2SEL_HW;
 	/*
@@ -1704,8 +1706,11 @@ static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
 	atslave->dma_dev = &dmac_pdev->dev;
 
 	chan = dma_request_channel(mask, at_dma_filter, atslave);
-	if (!chan)
+	if (!chan) {
+		put_device(&dmac_pdev->dev);
+		kfree(atslave);
 		return NULL;
+	}
 
 	atchan = to_at_dma_chan(chan);
 	atchan->per_if = dma_spec->args[0] & 0xff;
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 09410971615c..d2dd387c95d8 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1434,8 +1434,7 @@ amdgpu_dm_update_connector_after_detect(struct amdgpu_dm_connector *aconnector)
 
 			drm_connector_update_edid_property(connector,
 							   aconnector->edid);
-			aconnector->num_modes = drm_add_edid_modes(connector, aconnector->edid);
-			drm_connector_list_update(connector);
+			drm_add_edid_modes(connector, aconnector->edid);
 
 			if (aconnector->dc_link->aux_mode)
 				drm_dp_cec_set_edid(&aconnector->dm_dp_aux.aux,
diff --git a/drivers/iio/imu/bmi160/bmi160.h b/drivers/iio/imu/bmi160/bmi160.h
index 621f5309d735..431f10c2b951 100644
--- a/drivers/iio/imu/bmi160/bmi160.h
+++ b/drivers/iio/imu/bmi160/bmi160.h
@@ -7,6 +7,13 @@
 struct bmi160_data {
 	struct regmap *regmap;
 	struct iio_trigger *trig;
+	/*
+	 * Ensure natural alignment for timestamp if present.
+	 * Max length needed: 2 * 3 channels + 4 bytes padding + 8 byte ts.
+	 * If fewer channels are enabled, less space may be needed, as
+	 * long as the timestamp is still aligned to 8 bytes.
+	 */
+	__le16 buf[12] __aligned(8);
 };
 
 extern const struct regmap_config bmi160_regmap_config;
diff --git a/drivers/iio/imu/bmi160/bmi160_core.c b/drivers/iio/imu/bmi160/bmi160_core.c
index a5994899e396..088694c82327 100644
--- a/drivers/iio/imu/bmi160/bmi160_core.c
+++ b/drivers/iio/imu/bmi160/bmi160_core.c
@@ -411,8 +411,6 @@ static irqreturn_t bmi160_trigger_handler(int irq, void *p)
 	struct iio_poll_func *pf = p;
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct bmi160_data *data = iio_priv(indio_dev);
-	__le16 buf[12];
-	/* 2 sens x 3 axis x __le16 + 2 x __le16 pad + 4 x __le16 tstamp */
 	int i, ret, j = 0, base = BMI160_REG_DATA_MAGN_XOUT_L;
 	__le16 sample;
 
@@ -422,10 +420,10 @@ static irqreturn_t bmi160_trigger_handler(int irq, void *p)
 				       &sample, sizeof(sample));
 		if (ret)
 			goto done;
-		buf[j++] = sample;
+		data->buf[j++] = sample;
 	}
 
-	iio_push_to_buffers_with_timestamp(indio_dev, buf, pf->timestamp);
+	iio_push_to_buffers_with_timestamp(indio_dev, data->buf, pf->timestamp);
 done:
 	iio_trigger_notify_done(indio_dev->trig);
 	return IRQ_HANDLED;
diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 671700af9180..0d21c68bfe24 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -317,10 +317,6 @@ static int spinand_write_to_cache_op(struct spinand_device *spinand,
 		buf += ret;
 	}
 
-	if (req->ooblen)
-		memcpy(req->oobbuf.in, spinand->oobbuf + req->ooboffs,
-		       req->ooblen);
-
 	return 0;
 }
 
diff --git a/drivers/net/wireless/marvell/mwifiex/join.c b/drivers/net/wireless/marvell/mwifiex/join.c
index d87aeff70cef..c2cb1e711c06 100644
--- a/drivers/net/wireless/marvell/mwifiex/join.c
+++ b/drivers/net/wireless/marvell/mwifiex/join.c
@@ -877,6 +877,8 @@ mwifiex_cmd_802_11_ad_hoc_start(struct mwifiex_private *priv,
 
 	memset(adhoc_start->ssid, 0, IEEE80211_MAX_SSID_LEN);
 
+	if (req_ssid->ssid_len > IEEE80211_MAX_SSID_LEN)
+		req_ssid->ssid_len = IEEE80211_MAX_SSID_LEN;
 	memcpy(adhoc_start->ssid, req_ssid->ssid, req_ssid->ssid_len);
 
 	mwifiex_dbg(adapter, INFO, "info: ADHOC_S_CMD: SSID = %s\n",
diff --git a/fs/exec.c b/fs/exec.c
index 2441eb1a1e2d..1b4d2206d53a 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1009,8 +1009,8 @@ EXPORT_SYMBOL(read_code);
 
 /*
  * Maps the mm_struct mm into the current task struct.
- * On success, this function returns with the mutex
- * exec_update_mutex locked.
+ * On success, this function returns with exec_update_lock
+ * held for writing.
  */
 static int exec_mmap(struct mm_struct *mm)
 {
@@ -1023,7 +1023,7 @@ static int exec_mmap(struct mm_struct *mm)
 	old_mm = current->mm;
 	exec_mm_release(tsk, old_mm);
 
-	ret = mutex_lock_killable(&tsk->signal->exec_update_mutex);
+	ret = down_write_killable(&tsk->signal->exec_update_lock);
 	if (ret)
 		return ret;
 
@@ -1038,7 +1038,7 @@ static int exec_mmap(struct mm_struct *mm)
 		down_read(&old_mm->mmap_sem);
 		if (unlikely(old_mm->core_state)) {
 			up_read(&old_mm->mmap_sem);
-			mutex_unlock(&tsk->signal->exec_update_mutex);
+			up_write(&tsk->signal->exec_update_lock);
 			return -EINTR;
 		}
 	}
@@ -1450,7 +1450,7 @@ static void free_bprm(struct linux_binprm *bprm)
 	free_arg_pages(bprm);
 	if (bprm->cred) {
 		if (bprm->called_exec_mmap)
-			mutex_unlock(&current->signal->exec_update_mutex);
+			up_write(&current->signal->exec_update_lock);
 		mutex_unlock(&current->signal->cred_guard_mutex);
 		abort_creds(bprm->cred);
 	}
@@ -1500,7 +1500,7 @@ void install_exec_creds(struct linux_binprm *bprm)
 	 * credentials; any time after this it may be unlocked.
 	 */
 	security_bprm_committed_creds(bprm);
-	mutex_unlock(&current->signal->exec_update_mutex);
+	up_write(&current->signal->exec_update_lock);
 	mutex_unlock(&current->signal->cred_guard_mutex);
 }
 EXPORT_SYMBOL(install_exec_creds);
diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
index 5a48cee6d7d3..f529075a2ce8 100644
--- a/fs/fuse/acl.c
+++ b/fs/fuse/acl.c
@@ -19,6 +19,9 @@ struct posix_acl *fuse_get_acl(struct inode *inode, int type)
 	void *value = NULL;
 	struct posix_acl *acl;
 
+	if (fuse_is_bad(inode))
+		return ERR_PTR(-EIO);
+
 	if (!fc->posix_acl || fc->no_getxattr)
 		return NULL;
 
@@ -53,6 +56,9 @@ int fuse_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 	const char *name;
 	int ret;
 
+	if (fuse_is_bad(inode))
+		return -EIO;
+
 	if (!fc->posix_acl || fc->no_setxattr)
 		return -EOPNOTSUPP;
 
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index ee190119f45c..60378f3baaae 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -201,7 +201,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
 	int ret;
 
 	inode = d_inode_rcu(entry);
-	if (inode && is_bad_inode(inode))
+	if (inode && fuse_is_bad(inode))
 		goto invalid;
 	else if (time_before64(fuse_dentry_time(entry), get_jiffies_64()) ||
 		 (flags & LOOKUP_REVAL)) {
@@ -386,6 +386,9 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
 	bool outarg_valid = true;
 	bool locked;
 
+	if (fuse_is_bad(dir))
+		return ERR_PTR(-EIO);
+
 	locked = fuse_lock_inode(dir);
 	err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name,
 			       &outarg, &inode);
@@ -529,6 +532,9 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
 	struct fuse_conn *fc = get_fuse_conn(dir);
 	struct dentry *res = NULL;
 
+	if (fuse_is_bad(dir))
+		return -EIO;
+
 	if (d_in_lookup(entry)) {
 		res = fuse_lookup(dir, entry, 0);
 		if (IS_ERR(res))
@@ -577,6 +583,9 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args,
 	int err;
 	struct fuse_forget_link *forget;
 
+	if (fuse_is_bad(dir))
+		return -EIO;
+
 	forget = fuse_alloc_forget();
 	if (!forget)
 		return -ENOMEM;
@@ -704,6 +713,9 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
 	struct fuse_conn *fc = get_fuse_conn(dir);
 	FUSE_ARGS(args);
 
+	if (fuse_is_bad(dir))
+		return -EIO;
+
 	args.opcode = FUSE_UNLINK;
 	args.nodeid = get_node_id(dir);
 	args.in_numargs = 1;
@@ -740,6 +752,9 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry)
 	struct fuse_conn *fc = get_fuse_conn(dir);
 	FUSE_ARGS(args);
 
+	if (fuse_is_bad(dir))
+		return -EIO;
+
 	args.opcode = FUSE_RMDIR;
 	args.nodeid = get_node_id(dir);
 	args.in_numargs = 1;
@@ -818,6 +833,9 @@ static int fuse_rename2(struct inode *olddir, struct dentry *oldent,
 	struct fuse_conn *fc = get_fuse_conn(olddir);
 	int err;
 
+	if (fuse_is_bad(olddir))
+		return -EIO;
+
 	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
 		return -EINVAL;
 
@@ -953,7 +971,7 @@ static int fuse_do_getattr(struct inode *inode, struct kstat *stat,
 	if (!err) {
 		if (fuse_invalid_attr(&outarg.attr) ||
 		    (inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
-			make_bad_inode(inode);
+			fuse_make_bad(inode);
 			err = -EIO;
 		} else {
 			fuse_change_attributes(inode, &outarg.attr,
@@ -1155,6 +1173,9 @@ static int fuse_permission(struct inode *inode, int mask)
 	bool refreshed = false;
 	int err = 0;
 
+	if (fuse_is_bad(inode))
+		return -EIO;
+
 	if (!fuse_allow_current_process(fc))
 		return -EACCES;
 
@@ -1250,7 +1271,7 @@ static const char *fuse_get_link(struct dentry *dentry, struct inode *inode,
 	int err;
 
 	err = -EIO;
-	if (is_bad_inode(inode))
+	if (fuse_is_bad(inode))
 		goto out_err;
 
 	if (fc->cache_symlinks)
@@ -1298,7 +1319,7 @@ static int fuse_dir_fsync(struct file *file, loff_t start, loff_t end,
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	int err;
 
-	if (is_bad_inode(inode))
+	if (fuse_is_bad(inode))
 		return -EIO;
 
 	if (fc->no_fsyncdir)
@@ -1575,7 +1596,7 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
 
 	if (fuse_invalid_attr(&outarg.attr) ||
 	    (inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
-		make_bad_inode(inode);
+		fuse_make_bad(inode);
 		err = -EIO;
 		goto error;
 	}
@@ -1631,6 +1652,9 @@ static int fuse_setattr(struct dentry *entry, struct iattr *attr)
 	struct file *file = (attr->ia_valid & ATTR_FILE) ? attr->ia_file : NULL;
 	int ret;
 
+	if (fuse_is_bad(inode))
+		return -EIO;
+
 	if (!fuse_allow_current_process(get_fuse_conn(inode)))
 		return -EACCES;
 
@@ -1689,6 +1713,9 @@ static int fuse_getattr(const struct path *path, struct kstat *stat,
 	struct inode *inode = d_inode(path->dentry);
 	struct fuse_conn *fc = get_fuse_conn(inode);
 
+	if (fuse_is_bad(inode))
+		return -EIO;
+
 	if (!fuse_allow_current_process(fc))
 		return -EACCES;
 
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index ab4fc1255aca..1e1aef1bc20b 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -222,6 +222,9 @@ int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
 			  fc->atomic_o_trunc &&
 			  fc->writeback_cache;
 
+	if (fuse_is_bad(inode))
+		return -EIO;
+
 	err = generic_file_open(inode, file);
 	if (err)
 		return err;
@@ -443,7 +446,7 @@ static int fuse_flush(struct file *file, fl_owner_t id)
 	FUSE_ARGS(args);
 	int err;
 
-	if (is_bad_inode(inode))
+	if (fuse_is_bad(inode))
 		return -EIO;
 
 	if (fc->no_flush)
@@ -506,7 +509,7 @@ static int fuse_fsync(struct file *file, loff_t start, loff_t end,
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	int err;
 
-	if (is_bad_inode(inode))
+	if (fuse_is_bad(inode))
 		return -EIO;
 
 	inode_lock(inode);
@@ -830,7 +833,7 @@ static int fuse_readpage(struct file *file, struct page *page)
 	int err;
 
 	err = -EIO;
-	if (is_bad_inode(inode))
+	if (fuse_is_bad(inode))
 		goto out;
 
 	err = fuse_do_readpage(file, page);
@@ -973,7 +976,7 @@ static int fuse_readpages(struct file *file, struct address_space *mapping,
 	int err;
 
 	err = -EIO;
-	if (is_bad_inode(inode))
+	if (fuse_is_bad(inode))
 		goto out;
 
 	data.file = file;
@@ -1569,7 +1572,7 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	struct file *file = iocb->ki_filp;
 	struct fuse_file *ff = file->private_data;
 
-	if (is_bad_inode(file_inode(file)))
+	if (fuse_is_bad(file_inode(file)))
 		return -EIO;
 
 	if (!(ff->open_flags & FOPEN_DIRECT_IO))
@@ -1583,7 +1586,7 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct file *file = iocb->ki_filp;
 	struct fuse_file *ff = file->private_data;
 
-	if (is_bad_inode(file_inode(file)))
+	if (fuse_is_bad(file_inode(file)))
 		return -EIO;
 
 	if (!(ff->open_flags & FOPEN_DIRECT_IO))
@@ -2133,7 +2136,7 @@ static int fuse_writepages(struct address_space *mapping,
 	int err;
 
 	err = -EIO;
-	if (is_bad_inode(inode))
+	if (fuse_is_bad(inode))
 		goto out;
 
 	data.inode = inode;
@@ -2911,7 +2914,7 @@ long fuse_ioctl_common(struct file *file, unsigned int cmd,
 	if (!fuse_allow_current_process(fc))
 		return -EACCES;
 
-	if (is_bad_inode(inode))
+	if (fuse_is_bad(inode))
 		return -EIO;
 
 	return fuse_do_ioctl(file, cmd, arg, flags);
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index d7cde216fc87..e3688312e9f1 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -158,6 +158,8 @@ enum {
 	FUSE_I_INIT_RDPLUS,
 	/** An operation changing file size is in progress  */
 	FUSE_I_SIZE_UNSTABLE,
+	/* Bad inode */
+	FUSE_I_BAD,
 };
 
 struct fuse_conn;
@@ -787,6 +789,16 @@ static inline u64 fuse_get_attr_version(struct fuse_conn *fc)
 	return atomic64_read(&fc->attr_version);
 }
 
+static inline void fuse_make_bad(struct inode *inode)
+{
+	set_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state);
+}
+
+static inline bool fuse_is_bad(struct inode *inode)
+{
+	return unlikely(test_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state));
+}
+
 /** Device operations */
 extern const struct file_operations fuse_dev_operations;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index f58ab84b09fb..aa1d5cf1bc3a 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -115,7 +115,7 @@ static void fuse_evict_inode(struct inode *inode)
 		fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup);
 		fi->forget = NULL;
 	}
-	if (S_ISREG(inode->i_mode) && !is_bad_inode(inode)) {
+	if (S_ISREG(inode->i_mode) && !fuse_is_bad(inode)) {
 		WARN_ON(!list_empty(&fi->write_files));
 		WARN_ON(!list_empty(&fi->queued_writes));
 	}
@@ -306,7 +306,7 @@ struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
 		unlock_new_inode(inode);
 	} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
 		/* Inode has changed type, any I/O on the old should fail */
-		make_bad_inode(inode);
+		fuse_make_bad(inode);
 		iput(inode);
 		goto retry;
 	}
diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c
index 6a40f75a0d25..70f685b61e3a 100644
--- a/fs/fuse/readdir.c
+++ b/fs/fuse/readdir.c
@@ -207,7 +207,7 @@ static int fuse_direntplus_link(struct file *file,
 			dput(dentry);
 			goto retry;
 		}
-		if (is_bad_inode(inode)) {
+		if (fuse_is_bad(inode)) {
 			dput(dentry);
 			return -EIO;
 		}
@@ -568,7 +568,7 @@ int fuse_readdir(struct file *file, struct dir_context *ctx)
 	struct inode *inode = file_inode(file);
 	int err;
 
-	if (is_bad_inode(inode))
+	if (fuse_is_bad(inode))
 		return -EIO;
 
 	mutex_lock(&ff->readdir.lock);
diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c
index 20d052e08b3b..28fed5295770 100644
--- a/fs/fuse/xattr.c
+++ b/fs/fuse/xattr.c
@@ -113,6 +113,9 @@ ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size)
 	struct fuse_getxattr_out outarg;
 	ssize_t ret;
 
+	if (fuse_is_bad(inode))
+		return -EIO;
+
 	if (!fuse_allow_current_process(fc))
 		return -EACCES;
 
@@ -178,6 +181,9 @@ static int fuse_xattr_get(const struct xattr_handler *handler,
 			 struct dentry *dentry, struct inode *inode,
 			 const char *name, void *value, size_t size)
 {
+	if (fuse_is_bad(inode))
+		return -EIO;
+
 	return fuse_getxattr(inode, name, value, size);
 }
 
@@ -186,6 +192,9 @@ static int fuse_xattr_set(const struct xattr_handler *handler,
 			  const char *name, const void *value, size_t size,
 			  int flags)
 {
+	if (fuse_is_bad(inode))
+		return -EIO;
+
 	if (!value)
 		return fuse_removexattr(inode, name);
 
diff --git a/fs/proc/base.c b/fs/proc/base.c
index b690074e65ff..653c2d8aa1cd 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -403,11 +403,11 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
 
 static int lock_trace(struct task_struct *task)
 {
-	int err = mutex_lock_killable(&task->signal->exec_update_mutex);
+	int err = down_read_killable(&task->signal->exec_update_lock);
 	if (err)
 		return err;
 	if (!ptrace_may_access(task, PTRACE_MODE_ATTACH_FSCREDS)) {
-		mutex_unlock(&task->signal->exec_update_mutex);
+		up_read(&task->signal->exec_update_lock);
 		return -EPERM;
 	}
 	return 0;
@@ -415,7 +415,7 @@ static int lock_trace(struct task_struct *task)
 
 static void unlock_trace(struct task_struct *task)
 {
-	mutex_unlock(&task->signal->exec_update_mutex);
+	up_read(&task->signal->exec_update_lock);
 }
 
 #ifdef CONFIG_STACKTRACE
@@ -2769,7 +2769,7 @@ static int do_io_accounting(struct task_struct *task, struct seq_file *m, int wh
 	unsigned long flags;
 	int result;
 
-	result = mutex_lock_killable(&task->signal->exec_update_mutex);
+	result = down_read_killable(&task->signal->exec_update_lock);
 	if (result)
 		return result;
 
@@ -2805,7 +2805,7 @@ static int do_io_accounting(struct task_struct *task, struct seq_file *m, int wh
 	result = 0;
 
 out_unlock:
-	mutex_unlock(&task->signal->exec_update_mutex);
+	up_read(&task->signal->exec_update_lock);
 	return result;
 }
 
diff --git a/include/linux/kdev_t.h b/include/linux/kdev_t.h
index 85b5151911cf..4856706fbfeb 100644
--- a/include/linux/kdev_t.h
+++ b/include/linux/kdev_t.h
@@ -21,61 +21,61 @@
 	})
 
 /* acceptable for old filesystems */
-static inline bool old_valid_dev(dev_t dev)
+static __always_inline bool old_valid_dev(dev_t dev)
 {
 	return MAJOR(dev) < 256 && MINOR(dev) < 256;
 }
 
-static inline u16 old_encode_dev(dev_t dev)
+static __always_inline u16 old_encode_dev(dev_t dev)
 {
 	return (MAJOR(dev) << 8) | MINOR(dev);
 }
 
-static inline dev_t old_decode_dev(u16 val)
+static __always_inline dev_t old_decode_dev(u16 val)
 {
 	return MKDEV((val >> 8) & 255, val & 255);
 }
 
-static inline u32 new_encode_dev(dev_t dev)
+static __always_inline u32 new_encode_dev(dev_t dev)
 {
 	unsigned major = MAJOR(dev);
 	unsigned minor = MINOR(dev);
 	return (minor & 0xff) | (major << 8) | ((minor & ~0xff) << 12);
 }
 
-static inline dev_t new_decode_dev(u32 dev)
+static __always_inline dev_t new_decode_dev(u32 dev)
 {
 	unsigned major = (dev & 0xfff00) >> 8;
 	unsigned minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);
 	return MKDEV(major, minor);
 }
 
-static inline u64 huge_encode_dev(dev_t dev)
+static __always_inline u64 huge_encode_dev(dev_t dev)
 {
 	return new_encode_dev(dev);
 }
 
-static inline dev_t huge_decode_dev(u64 dev)
+static __always_inline dev_t huge_decode_dev(u64 dev)
 {
 	return new_decode_dev(dev);
 }
 
-static inline int sysv_valid_dev(dev_t dev)
+static __always_inline int sysv_valid_dev(dev_t dev)
 {
 	return MAJOR(dev) < (1<<14) && MINOR(dev) < (1<<18);
 }
 
-static inline u32 sysv_encode_dev(dev_t dev)
+static __always_inline u32 sysv_encode_dev(dev_t dev)
 {
 	return MINOR(dev) | (MAJOR(dev) << 18);
 }
 
-static inline unsigned sysv_major(u32 dev)
+static __always_inline unsigned sysv_major(u32 dev)
 {
 	return (dev >> 18) & 0x3fff;
 }
 
-static inline unsigned sysv_minor(u32 dev)
+static __always_inline unsigned sysv_minor(u32 dev)
 {
 	return dev & 0x3ffff;
 }
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 00d6054687dd..8a3606372abc 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -125,6 +125,7 @@ static inline int rwsem_is_contended(struct rw_semaphore *sem)
  * lock for reading
  */
 extern void down_read(struct rw_semaphore *sem);
+extern int __must_check down_read_interruptible(struct rw_semaphore *sem);
 extern int __must_check down_read_killable(struct rw_semaphore *sem);
 
 /*
@@ -173,6 +174,7 @@ extern void downgrade_write(struct rw_semaphore *sem);
  * See Documentation/locking/lockdep-design.rst for more details.)
  */
 extern void down_read_nested(struct rw_semaphore *sem, int subclass);
+extern int __must_check down_read_killable_nested(struct rw_semaphore *sem, int subclass);
 extern void down_write_nested(struct rw_semaphore *sem, int subclass);
 extern int down_write_killable_nested(struct rw_semaphore *sem, int subclass);
 extern void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest_lock);
@@ -193,6 +195,7 @@ extern void down_read_non_owner(struct rw_semaphore *sem);
 extern void up_read_non_owner(struct rw_semaphore *sem);
 #else
 # define down_read_nested(sem, subclass)		down_read(sem)
+# define down_read_killable_nested(sem, subclass)	down_read_killable(sem)
 # define down_write_nest_lock(sem, nest_lock)	down_write(sem)
 # define down_write_nested(sem, subclass)	down_write(sem)
 # define down_write_killable_nested(sem, subclass)	down_write_killable(sem)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index a29df79540ce..baf58f4cb057 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -226,12 +226,13 @@ struct signal_struct {
 					 * credential calculations
 					 * (notably. ptrace)
 					 * Deprecated do not use in new code.
-					 * Use exec_update_mutex instead.
-					 */
-	struct mutex exec_update_mutex;	/* Held while task_struct is being
-					 * updated during exec, and may have
-					 * inconsistent permissions.
+					 * Use exec_update_lock instead.
 					 */
+	struct rw_semaphore exec_update_lock;	/* Held while task_struct is
+						 * being updated during exec,
+						 * and may have inconsistent
+						 * permissions.
+						 */
 } __randomize_layout;
 
 /*
diff --git a/init/init_task.c b/init/init_task.c
index bd403ed3e418..df7041be96fc 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -26,7 +26,7 @@ static struct signal_struct init_signals = {
 	.multiprocess	= HLIST_HEAD_INIT,
 	.rlim		= INIT_RLIMITS,
 	.cred_guard_mutex = __MUTEX_INITIALIZER(init_signals.cred_guard_mutex),
-	.exec_update_mutex = __MUTEX_INITIALIZER(init_signals.exec_update_mutex),
+	.exec_update_lock = __RWSEM_INITIALIZER(init_signals.exec_update_lock),
 #ifdef CONFIG_POSIX_TIMERS
 	.posix_timers = LIST_HEAD_INIT(init_signals.posix_timers),
 	.cputimer	= {
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9f7c2da99299..2ef33e9a7591 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1254,7 +1254,7 @@ static void put_ctx(struct perf_event_context *ctx)
  * function.
  *
  * Lock order:
- *    exec_update_mutex
+ *    exec_update_lock
  *	task_struct::perf_event_mutex
  *	  perf_event_context::mutex
  *	    perf_event::child_mutex;
@@ -11001,24 +11001,6 @@ SYSCALL_DEFINE5(perf_event_open,
 		goto err_task;
 	}
 
-	if (task) {
-		err = mutex_lock_interruptible(&task->signal->exec_update_mutex);
-		if (err)
-			goto err_task;
-
-		/*
-		 * Reuse ptrace permission checks for now.
-		 *
-		 * We must hold exec_update_mutex across this and any potential
-		 * perf_install_in_context() call for this new event to
-		 * serialize against exec() altering our credentials (and the
-		 * perf_event_exit_task() that could imply).
-		 */
-		err = -EACCES;
-		if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS))
-			goto err_cred;
-	}
-
 	if (flags & PERF_FLAG_PID_CGROUP)
 		cgroup_fd = pid;
 
@@ -11026,7 +11008,7 @@ SYSCALL_DEFINE5(perf_event_open,
 				 NULL, NULL, cgroup_fd);
 	if (IS_ERR(event)) {
 		err = PTR_ERR(event);
-		goto err_cred;
+		goto err_task;
 	}
 
 	if (is_sampling_event(event)) {
@@ -11145,6 +11127,24 @@ SYSCALL_DEFINE5(perf_event_open,
 		goto err_context;
 	}
 
+	if (task) {
+		err = down_read_interruptible(&task->signal->exec_update_lock);
+		if (err)
+			goto err_file;
+
+		/*
+		 * Preserve ptrace permission check for backwards compatibility.
+		 *
+		 * We must hold exec_update_lock across this and any potential
+		 * perf_install_in_context() call for this new event to
+		 * serialize against exec() altering our credentials (and the
+		 * perf_event_exit_task() that could imply).
+		 */
+		err = -EACCES;
+		if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS))
+			goto err_cred;
+	}
+
 	if (move_group) {
 		gctx = __perf_event_ctx_lock_double(group_leader, ctx);
 
@@ -11298,7 +11298,7 @@ SYSCALL_DEFINE5(perf_event_open,
 	mutex_unlock(&ctx->mutex);
 
 	if (task) {
-		mutex_unlock(&task->signal->exec_update_mutex);
+		up_read(&task->signal->exec_update_lock);
 		put_task_struct(task);
 	}
 
@@ -11320,7 +11320,10 @@ SYSCALL_DEFINE5(perf_event_open,
 	if (move_group)
 		perf_event_ctx_unlock(group_leader, gctx);
 	mutex_unlock(&ctx->mutex);
-/* err_file: */
+err_cred:
+	if (task)
+		up_read(&task->signal->exec_update_lock);
+err_file:
 	fput(event_file);
 err_context:
 	perf_unpin_context(ctx);
@@ -11332,9 +11335,6 @@ SYSCALL_DEFINE5(perf_event_open,
 	 */
 	if (!event_file)
 		free_event(event);
-err_cred:
-	if (task)
-		mutex_unlock(&task->signal->exec_update_mutex);
 err_task:
 	if (task)
 		put_task_struct(task);
@@ -11639,7 +11639,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
 /*
  * When a child task exits, feed back event values to parent events.
  *
- * Can be called with exec_update_mutex held when called from
+ * Can be called with exec_update_lock held when called from
  * install_exec_creds().
  */
 void perf_event_exit_task(struct task_struct *child)
diff --git a/kernel/fork.c b/kernel/fork.c
index 419fff8eb9e5..50f37d5afb32 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1221,7 +1221,7 @@ struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
 	struct mm_struct *mm;
 	int err;
 
-	err =  mutex_lock_killable(&task->signal->exec_update_mutex);
+	err =  down_read_killable(&task->signal->exec_update_lock);
 	if (err)
 		return ERR_PTR(err);
 
@@ -1231,7 +1231,7 @@ struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
 		mmput(mm);
 		mm = ERR_PTR(-EACCES);
 	}
-	mutex_unlock(&task->signal->exec_update_mutex);
+	up_read(&task->signal->exec_update_lock);
 
 	return mm;
 }
@@ -1586,7 +1586,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
 	sig->oom_score_adj_min = current->signal->oom_score_adj_min;
 
 	mutex_init(&sig->cred_guard_mutex);
-	mutex_init(&sig->exec_update_mutex);
+	init_rwsem(&sig->exec_update_lock);
 
 	return 0;
 }
diff --git a/kernel/kcmp.c b/kernel/kcmp.c
index b3ff9288c6cc..c0d2ad9b4705 100644
--- a/kernel/kcmp.c
+++ b/kernel/kcmp.c
@@ -75,25 +75,25 @@ get_file_raw_ptr(struct task_struct *task, unsigned int idx)
 	return file;
 }
 
-static void kcmp_unlock(struct mutex *m1, struct mutex *m2)
+static void kcmp_unlock(struct rw_semaphore *l1, struct rw_semaphore *l2)
 {
-	if (likely(m2 != m1))
-		mutex_unlock(m2);
-	mutex_unlock(m1);
+	if (likely(l2 != l1))
+		up_read(l2);
+	up_read(l1);
 }
 
-static int kcmp_lock(struct mutex *m1, struct mutex *m2)
+static int kcmp_lock(struct rw_semaphore *l1, struct rw_semaphore *l2)
 {
 	int err;
 
-	if (m2 > m1)
-		swap(m1, m2);
+	if (l2 > l1)
+		swap(l1, l2);
 
-	err = mutex_lock_killable(m1);
-	if (!err && likely(m1 != m2)) {
-		err = mutex_lock_killable_nested(m2, SINGLE_DEPTH_NESTING);
+	err = down_read_killable(l1);
+	if (!err && likely(l1 != l2)) {
+		err = down_read_killable_nested(l2, SINGLE_DEPTH_NESTING);
 		if (err)
-			mutex_unlock(m1);
+			up_read(l1);
 	}
 
 	return err;
@@ -173,8 +173,8 @@ SYSCALL_DEFINE5(kcmp, pid_t, pid1, pid_t, pid2, int, type,
 	/*
 	 * One should have enough rights to inspect task details.
 	 */
-	ret = kcmp_lock(&task1->signal->exec_update_mutex,
-			&task2->signal->exec_update_mutex);
+	ret = kcmp_lock(&task1->signal->exec_update_lock,
+			&task2->signal->exec_update_lock);
 	if (ret)
 		goto err;
 	if (!ptrace_may_access(task1, PTRACE_MODE_READ_REALCREDS) ||
@@ -229,8 +229,8 @@ SYSCALL_DEFINE5(kcmp, pid_t, pid1, pid_t, pid2, int, type,
 	}
 
 err_unlock:
-	kcmp_unlock(&task1->signal->exec_update_mutex,
-		    &task2->signal->exec_update_mutex);
+	kcmp_unlock(&task1->signal->exec_update_lock,
+		    &task2->signal->exec_update_lock);
 err:
 	put_task_struct(task1);
 	put_task_struct(task2);
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index baafa1dd9fcc..5d54ff3179b8 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -1348,6 +1348,18 @@ inline void __down_read(struct rw_semaphore *sem)
 	}
 }
 
+static inline int __down_read_interruptible(struct rw_semaphore *sem)
+{
+	if (!rwsem_read_trylock(sem)) {
+		if (IS_ERR(rwsem_down_read_slowpath(sem, TASK_INTERRUPTIBLE)))
+			return -EINTR;
+		DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);
+	} else {
+		rwsem_set_reader_owned(sem);
+	}
+	return 0;
+}
+
 static inline int __down_read_killable(struct rw_semaphore *sem)
 {
 	if (!rwsem_read_trylock(sem)) {
@@ -1498,6 +1510,20 @@ void __sched down_read(struct rw_semaphore *sem)
 }
 EXPORT_SYMBOL(down_read);
 
+int __sched down_read_interruptible(struct rw_semaphore *sem)
+{
+	might_sleep();
+	rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
+
+	if (LOCK_CONTENDED_RETURN(sem, __down_read_trylock, __down_read_interruptible)) {
+		rwsem_release(&sem->dep_map, 1, _RET_IP_);
+		return -EINTR;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(down_read_interruptible);
+
 int __sched down_read_killable(struct rw_semaphore *sem)
 {
 	might_sleep();
@@ -1608,6 +1634,20 @@ void down_read_nested(struct rw_semaphore *sem, int subclass)
 }
 EXPORT_SYMBOL(down_read_nested);
 
+int down_read_killable_nested(struct rw_semaphore *sem, int subclass)
+{
+	might_sleep();
+	rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_);
+
+	if (LOCK_CONTENDED_RETURN(sem, __down_read_trylock, __down_read_killable)) {
+		rwsem_release(&sem->dep_map, 1, _RET_IP_);
+		return -EINTR;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(down_read_killable_nested);
+
 void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest)
 {
 	might_sleep();

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