From: Matthew Wilcox <willy@infradead.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>,
ntfs3@lists.linux.dev,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 5/8] fs/ntfs3: Use kvmalloc instead of kmalloc(... __GFP_NOWARN)
Date: Sat, 23 Dec 2023 16:56:50 +0000 [thread overview]
Message-ID: <ZYcRUvZXiaKtiANz@casper.infradead.org> (raw)
In-Reply-To: <bca8d526-2397-4ca5-b1d6-5758c9334a81@I-love.SAKURA.ne.jp>
On Sat, Dec 23, 2023 at 10:33:11PM +0900, Tetsuo Handa wrote:
> But you can't replace GFP_NOFS with GFP_KERNEL anyway, for syzbot is also
> reporting GFP_KERNEL allocation with filesystem lock held
> at https://syzkaller.appspot.com/bug?extid=18f543fc90dd1194c616 .
Well, you _can_. What _all_ filesystem authors should be doing is
switching to memalloc_nofs_save/restore. Generally when taking a lock
that's needed during reclaim. In this specific case, soemthing like
this:
diff --git a/fs/ntfs3/record.c b/fs/ntfs3/record.c
index 7b6423584eae..432905489a14 100644
--- a/fs/ntfs3/record.c
+++ b/fs/ntfs3/record.c
@@ -122,6 +122,7 @@ int mi_read(struct mft_inode *mi, bool is_mft)
struct ntfs_inode *mft_ni = sbi->mft.ni;
struct runs_tree *run = mft_ni ? &mft_ni->file.run : NULL;
struct rw_semaphore *rw_lock = NULL;
+ unsigned int memalloc = memalloc_nofs_save();
if (is_mounted(sbi)) {
if (!is_mft && mft_ni) {
@@ -177,6 +178,7 @@ int mi_read(struct mft_inode *mi, bool is_mft)
goto out;
}
+ memalloc_nofs_restore(memalloc);
return 0;
out:
@@ -186,6 +188,7 @@ int mi_read(struct mft_inode *mi, bool is_mft)
err = -EINVAL;
}
+ memalloc_nofs_restore(memalloc);
return err;
}
next prev parent reply other threads:[~2023-12-23 16:56 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-03 7:23 [PATCH 0/8] fs/ntfs3: Bugfix and refactoring Konstantin Komarov
2023-07-03 7:24 ` [PATCH 1/8] fs/ntfs3: Add ckeck in ni_update_parent() Konstantin Komarov
2023-07-03 7:25 ` [PATCH 2/8] fs/ntfs3: Write immediately updated ntfs state Konstantin Komarov
2023-07-03 7:25 ` [PATCH 3/8] fs/ntfs3: Minor code refactoring and formatting Konstantin Komarov
2023-07-03 7:26 ` [PATCH 4/8] fs/ntfs3: Don't allow to change label if volume is read-only Konstantin Komarov
2023-07-03 7:26 ` [PATCH 5/8] fs/ntfs3: Use kvmalloc instead of kmalloc(... __GFP_NOWARN) Konstantin Komarov
2023-12-23 4:46 ` Matthew Wilcox
2023-12-23 13:33 ` Tetsuo Handa
2023-12-23 16:56 ` Matthew Wilcox [this message]
2023-07-03 7:27 ` [PATCH 6/8] fs/ntfs3: Add more attributes checks in mi_enum_attr() Konstantin Komarov
2023-07-03 7:27 ` [PATCH 7/8] fs/ntfs3: fix deadlock in mark_as_free_ex Konstantin Komarov
2023-07-03 7:28 ` [PATCH 8/8] fs/ntfs3: Fix shift-out-of-bounds in ntfs_fill_super Konstantin Komarov
2023-12-23 5:00 ` [PATCH 0/8] fs/ntfs3: Bugfix and refactoring Kent Overstreet
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