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[ Upstream commitfbd019737d] Ying triggered a call trace when doing an asconf testing: BUG: scheduling while atomic: swapper/12/0/0x10000100 Call Trace: <IRQ> [<ffffffffa4375904>] dump_stack+0x19/0x1b [<ffffffffa436fcaf>] __schedule_bug+0x64/0x72 [<ffffffffa437b93a>] __schedule+0x9ba/0xa00 [<ffffffffa3cd5326>] __cond_resched+0x26/0x30 [<ffffffffa437bc4a>] _cond_resched+0x3a/0x50 [<ffffffffa3e22be8>] kmem_cache_alloc_node+0x38/0x200 [<ffffffffa423512d>] __alloc_skb+0x5d/0x2d0 [<ffffffffc0995320>] sctp_packet_transmit+0x610/0xa20 [sctp] [<ffffffffc098510e>] sctp_outq_flush+0x2ce/0xc00 [sctp] [<ffffffffc098646c>] sctp_outq_uncork+0x1c/0x20 [sctp] [<ffffffffc0977338>] sctp_cmd_interpreter.isra.22+0xc8/0x1460 [sctp] [<ffffffffc0976ad1>] sctp_do_sm+0xe1/0x350 [sctp] [<ffffffffc099443d>] sctp_primitive_ASCONF+0x3d/0x50 [sctp] [<ffffffffc0977384>] sctp_cmd_interpreter.isra.22+0x114/0x1460 [sctp] [<ffffffffc0976ad1>] sctp_do_sm+0xe1/0x350 [sctp] [<ffffffffc097b3a4>] sctp_assoc_bh_rcv+0xf4/0x1b0 [sctp] [<ffffffffc09840f1>] sctp_inq_push+0x51/0x70 [sctp] [<ffffffffc099732b>] sctp_rcv+0xa8b/0xbd0 [sctp] As it shows, the first sctp_do_sm() running under atomic context (NET_RX softirq) invoked sctp_primitive_ASCONF() that uses GFP_KERNEL flag later, and this flag is supposed to be used in non-atomic context only. Besides, sctp_do_sm() was called recursively, which is not expected. Vlad tried to fix this recursive call in Commitc078669340("sctp: Fix oops when sending queued ASCONF chunks") by introducing a new command SCTP_CMD_SEND_NEXT_ASCONF. But it didn't work as this command is still used in the first sctp_do_sm() call, and sctp_primitive_ASCONF() will be called in this command again. To avoid calling sctp_do_sm() recursively, we send the next queued ASCONF not by sctp_primitive_ASCONF(), but by sctp_sf_do_prm_asconf() in the 1st sctp_do_sm() directly. Reported-by: Ying Xu <yinxu@redhat.com> Signed-off-by: Xin Long <lucien.xin@gmail.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.