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Mon, 7 Aug 2023 09:20:31 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 1uCAAV+30GTgHgAAMHmgww (envelope-from ); Mon, 07 Aug 2023 09:20:31 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 756D1A076C; Mon, 7 Aug 2023 11:20:30 +0200 (CEST) Date: Mon, 7 Aug 2023 11:20:30 +0200 From: Jan Kara To: Hugh Dickins Cc: Christian Brauner , Jan Kara , Carlos Maiolino , Dan Carpenter , Andrew Morton , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH vfs.tmpfs] shmem: move spinlock into shmem_recalc_inode() to fix quota support Message-ID: <20230807092030.krout2mwwa3yesd4@quack3> References: <29f48045-2cb5-7db-ecf1-72462f1bef5@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <29f48045-2cb5-7db-ecf1-72462f1bef5@google.com> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: C946CC0018 X-Stat-Signature: 1hprga34tsjx4uk3sjod1qzqcte7tqf4 X-Rspam-User: X-HE-Tag: 1691400032-604478 X-HE-Meta: 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 MLt5vQvE C+djRkO8qadBiwhs3c4FH+dBQbTbrm7fkFls34pz/HAz4TPFNcr47i6yLmxb4UdMOmoYl95aX2zwlzLSWlCe/wtNxFGFpucWPFYzB4c9aLpfEp+3prIJoXs/eP6kSb+ILm3bK35Q9G1d5bs6xTMNZrI8XBWnn6E5fbZSw/x4IjPVBCaDQuQN4GppeOhfjLWBuntKE4kGBPCLWiTyhztRc1eW/81AOWE7PTdNcyyDT0McK4Q/b58XEYMFhGYO70a4X0W/eMc8btOy/YqMU7rQY9q2vyu8umiKnTxYzFBRUSUmPEQHosZBOYr02xy6N25pDz36eZDRliHhuBDeCdzet2NeISvSc9stSLFZ+lpgmEDmSMpxTOv6jbSYbNPMENqn8M2mzUw4kZeMUlQe+PG5ISaCusCkGqyzO6iJy/xzSBC7C9UJ7WVQq5nU5o8MPmqwatAW1 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu 03-08-23 22:46:11, Hugh Dickins wrote: > Commit "shmem: fix quota lock nesting in huge hole handling" was not so > good: Smatch caught shmem_recalc_inode()'s shmem_inode_unacct_blocks() > descending into quota_send_warning(): where blocking GFP_NOFS is used, > yet shmem_recalc_inode() is called holding the shmem inode's info->lock. > > Yes, both __dquot_alloc_space() and __dquot_free_space() are commented > "This operation can block, but only after everything is updated" - when > calling flush_warnings() at the end - both its print_warning() and its > quota_send_warning() may block. > > Rework shmem_recalc_inode() to take the shmem inode's info->lock inside, > and drop it before calling shmem_inode_unacct_blocks(). > > And why were the spin_locks disabling interrupts? That was just a relic > from when shmem_charge() and shmem_uncharge() were called while holding > i_pages xa_lock: stop disabling interrupts for info->lock now. > > To help stop me from making the same mistake again, add a might_sleep() > into shmem_inode_acct_block() and shmem_inode_unacct_blocks(); and those > functions have grown, so let the compiler decide whether to inline them. > > Reported-by: Dan Carpenter > Closes: https://lore.kernel.org/linux-fsdevel/ffd7ca34-7f2a-44ee-b05d-b54d920ce076@moroto.mountain/ > Signed-off-by: Hugh Dickins Thanks for the fix Hugh! The patch looks good to me so feel free to add: Reviewed-by: Jan Kara (FWIW for shmem code). Honza -- Jan Kara SUSE Labs, CR