kernel/linux.git/include/linux, branch v4.4.235

writeback: Avoid skipping inode writeback

2020-09-03T09:19:27+00:00

commit 5afced3bf28100d81fb2fe7e98918632a08feaf5 upstream. Inode's i_io_list list head is used to attach inode to several different lists - wb->{b_dirty, b_dirty_time, b_io, b_more_io}. When flush worker prepares a list of inodes to writeback e.g. for sync(2), it moves inodes to b_io list. Thus it is critical for sync(2) data integrity guarantees that inode is not requeued to any other writeback list when inode is queued for processing by flush worker. That's the reason why writeback_single_inode() does not touch i_io_list (unless the inode is completely clean) and why __mark_inode_dirty() does not touch i_io_list if I_SYNC flag is set. However there are two flaws in the current logic: 1) When inode has only I_DIRTY_TIME set but it is already queued in b_io list due to sync(2), concurrent __mark_inode_dirty(inode, I_DIRTY_SYNC) can still move inode back to b_dirty list resulting in skipping writeback of inode time stamps during sync(2). 2) When inode is on b_dirty_time list and writeback_single_inode() races with __mark_inode_dirty() like: writeback_single_inode() __mark_inode_dirty(inode, I_DIRTY_PAGES) inode->i_state |= I_SYNC __writeback_single_inode() inode->i_state |= I_DIRTY_PAGES; if (inode->i_state & I_SYNC) bail if (!(inode->i_state & I_DIRTY_ALL)) - not true so nothing done We end up with I_DIRTY_PAGES inode on b_dirty_time list and thus standard background writeback will not writeback this inode leading to possible dirty throttling stalls etc. (thanks to Martijn Coenen for this analysis). Fix these problems by tracking whether inode is queued in b_io or b_more_io lists in a new I_SYNC_QUEUED flag. When this flag is set, we know flush worker has queued inode and we should not touch i_io_list. On the other hand we also know that once flush worker is done with the inode it will requeue the inode to appropriate dirty list. When I_SYNC_QUEUED is not set, __mark_inode_dirty() can (and must) move inode to appropriate dirty list. Reported-by: Martijn Coenen Reviewed-by: Martijn Coenen Tested-by: Martijn Coenen Reviewed-by: Christoph Hellwig Fixes: 0ae45f63d4ef ("vfs: add support for a lazytime mount option") CC: stable@vger.kernel.org Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

coredump: fix race condition between collapse_huge_page() and core dumping

2020-08-26T08:27:07+00:00

[ Upstream commit 59ea6d06cfa9247b586a695c21f94afa7183af74 ] When fixing the race conditions between the coredump and the mmap_sem holders outside the context of the process, we focused on mmget_not_zero()/get_task_mm() callers in 04f5866e41fb70 ("coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping"), but those aren't the only cases where the mmap_sem can be taken outside of the context of the process as Michal Hocko noticed while backporting that commit to older -stable kernels. If mmgrab() is called in the context of the process, but then the mm_count reference is transferred outside the context of the process, that can also be a problem if the mmap_sem has to be taken for writing through that mm_count reference. khugepaged registration calls mmgrab() in the context of the process, but the mmap_sem for writing is taken later in the context of the khugepaged kernel thread. collapse_huge_page() after taking the mmap_sem for writing doesn't modify any vma, so it's not obvious that it could cause a problem to the coredump, but it happens to modify the pmd in a way that breaks an invariant that pmd_trans_huge_lock() relies upon. collapse_huge_page() needs the mmap_sem for writing just to block concurrent page faults that call pmd_trans_huge_lock(). Specifically the invariant that "!pmd_trans_huge()" cannot become a "pmd_trans_huge()" doesn't hold while collapse_huge_page() runs. The coredump will call __get_user_pages() without mmap_sem for reading, which eventually can invoke a lockless page fault which will need a functional pmd_trans_huge_lock(). So collapse_huge_page() needs to use mmget_still_valid() to check it's not running concurrently with the coredump... as long as the coredump can invoke page faults without holding the mmap_sem for reading. This has "Fixes: khugepaged" to facilitate backporting, but in my view it's more a bug in the coredump code that will eventually have to be rewritten to stop invoking page faults without the mmap_sem for reading. So the long term plan is still to drop all mmget_still_valid(). Link: http://lkml.kernel.org/r/20190607161558.32104-1-aarcange@redhat.com Fixes: ba76149f47d8 ("thp: khugepaged") Signed-off-by: Andrea Arcangeli Reported-by: Michal Hocko Acked-by: Michal Hocko Acked-by: Kirill A. Shutemov Cc: Oleg Nesterov Cc: Jann Horn Cc: Hugh Dickins Cc: Mike Rapoport Cc: Mike Kravetz Cc: Peter Xu Cc: Jason Gunthorpe Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

iommu/vt-d: Enforce PASID devTLB field mask

2020-08-21T08:53:06+00:00

[ Upstream commit 5f77d6ca5ca74e4b4a5e2e010f7ff50c45dea326 ] Set proper masks to avoid invalid input spillover to reserved bits. Signed-off-by: Liu Yi L Signed-off-by: Jacob Pan Signed-off-by: Lu Baolu Reviewed-by: Eric Auger Link: https://lore.kernel.org/r/20200724014925.15523-2-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin

tracepoint: Mark __tracepoint_string's __used

2020-08-21T08:52:57+00:00

commit f3751ad0116fb6881f2c3c957d66a9327f69cefb upstream. __tracepoint_string's have their string data stored in .rodata, and an address to that data stored in the "__tracepoint_str" section. Functions that refer to those strings refer to the symbol of the address. Compiler optimization can replace those address references with references directly to the string data. If the address doesn't appear to have other uses, then it appears dead to the compiler and is removed. This can break the /tracing/printk_formats sysfs node which iterates the addresses stored in the "__tracepoint_str" section. Like other strings stored in custom sections in this header, mark these __used to inform the compiler that there are other non-obvious users of the address, so they should still be emitted. Link: https://lkml.kernel.org/r/20200730224555.2142154-2-ndesaulniers@google.com Cc: Ingo Molnar Cc: Miguel Ojeda Cc: stable@vger.kernel.org Fixes: 102c9323c35a8 ("tracing: Add __tracepoint_string() to export string pointers") Reported-by: Tim Murray Reported-by: Simon MacMullen Suggested-by: Greg Hackmann Signed-off-by: Nick Desaulniers Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman

random32: move the pseudo-random 32-bit definitions to prandom.h

2020-08-21T08:52:55+00:00

commit c0842fbc1b18c7a044e6ff3e8fa78bfa822c7d1a upstream. The addition of percpu.h to the list of includes in random.h revealed some circular dependencies on arm64 and possibly other platforms. This include was added solely for the pseudo-random definitions, which have nothing to do with the rest of the definitions in this file but are still there for legacy reasons. This patch moves the pseudo-random parts to linux/prandom.h and the percpu.h include with it, which is now guarded by _LINUX_PRANDOM_H and protected against recursive inclusion. A further cleanup step would be to remove this from entirely, and make people who use the prandom infrastructure include just the new header file. That's a bit of a churn patch, but grepping for "prandom_" and "next_pseudo_random32" "struct rnd_state" should catch most users. But it turns out that that nice cleanup step is fairly painful, because a _lot_ of code currently seems to depend on the implicit include of , which can currently come in a lot of ways, including such fairly core headfers as . So the "nice cleanup" part may or may never happen. Fixes: 1c9df907da83 ("random: fix circular include dependency on arm64 after addition of percpu.h") Tested-by: Guenter Roeck Acked-by: Willy Tarreau Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

random32: remove net_rand_state from the latent entropy gcc plugin

2020-08-21T08:52:55+00:00

commit 83bdc7275e6206f560d247be856bceba3e1ed8f2 upstream. It turns out that the plugin right now ends up being really unhappy about the change from 'static' to 'extern' storage that happened in commit f227e3ec3b5c ("random32: update the net random state on interrupt and activity"). This is probably a trivial fix for the latent_entropy plugin, but for now, just remove net_rand_state from the list of things the plugin worries about. Reported-by: Stephen Rothwell Cc: Emese Revfy Cc: Kees Cook Cc: Willy Tarreau Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

random: fix circular include dependency on arm64 after addition of percpu.h

2020-08-21T08:52:55+00:00

commit 1c9df907da83812e4f33b59d3d142c864d9da57f upstream. Daniel Díaz and Kees Cook independently reported that commit f227e3ec3b5c ("random32: update the net random state on interrupt and activity") broke arm64 due to a circular dependency on include files since the addition of percpu.h in random.h. The correct fix would definitely be to move all the prandom32 stuff out of random.h but for backporting, a smaller solution is preferred. This one replaces linux/percpu.h with asm/percpu.h, and this fixes the problem on x86_64, arm64, arm, and mips. Note that moving percpu.h around didn't change anything and that removing it entirely broke differently. When backporting, such options might still be considered if this patch fails to help. [ It turns out that an alternate fix seems to be to just remove the troublesome remove from the arm64 that causes the circular dependency. But we might as well do the whole belt-and-suspenders thing, and minimize inclusion in too. Either will fix the problem, and both are good changes. - Linus ] Reported-by: Daniel Díaz Reported-by: Kees Cook Tested-by: Marc Zyngier Fixes: f227e3ec3b5c Cc: Stephen Rothwell Signed-off-by: Willy Tarreau Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

random32: update the net random state on interrupt and activity

2020-08-21T08:52:54+00:00

commit f227e3ec3b5cad859ad15666874405e8c1bbc1d4 upstream. This modifies the first 32 bits out of the 128 bits of a random CPU's net_rand_state on interrupt or CPU activity to complicate remote observations that could lead to guessing the network RNG's internal state. Note that depending on some network devices' interrupt rate moderation or binding, this re-seeding might happen on every packet or even almost never. In addition, with NOHZ some CPUs might not even get timer interrupts, leaving their local state rarely updated, while they are running networked processes making use of the random state. For this reason, we also perform this update in update_process_times() in order to at least update the state when there is user or system activity, since it's the only case we care about. Reported-by: Amit Klein Suggested-by: Linus Torvalds Cc: Eric Dumazet Cc: "Jason A. Donenfeld" Cc: Andy Lutomirski Cc: Kees Cook Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Signed-off-by: Willy Tarreau Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

tcp: allow at most one TLP probe per flight

2020-07-31T14:43:16+00:00

[ Upstream commit 76be93fc0702322179bb0ea87295d820ee46ad14 ] Previously TLP may send multiple probes of new data in one flight. This happens when the sender is cwnd limited. After the initial TLP containing new data is sent, the sender receives another ACK that acks partial inflight. It may re-arm another TLP timer to send more, if no further ACK returns before the next TLP timeout (PTO) expires. The sender may send in theory a large amount of TLP until send queue is depleted. This only happens if the sender sees such irregular uncommon ACK pattern. But it is generally undesirable behavior during congestion especially. The original TLP design restrict only one TLP probe per inflight as published in "Reducing Web Latency: the Virtue of Gentle Aggression", SIGCOMM 2013. This patch changes TLP to send at most one probe per inflight. Note that if the sender is app-limited, TLP retransmits old data and did not have this issue. Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

usb: core: Add a helper function to check the validity of EP type in URB

2020-07-22T07:10:05+00:00

commit e901b9873876ca30a09253731bd3a6b00c44b5b0 upstream. This patch adds a new helper function to perform a sanity check of the given URB to see whether it contains a valid endpoint. It's a light- weight version of what usb_submit_urb() does, but without the kernel warning followed by the stack trace, just returns an error code. Especially for a driver that doesn't parse the descriptor but fills the URB with the fixed endpoint (e.g. some quirks for non-compliant devices), this kind of check is preferable at the probe phase before actually submitting the urb. Tested-by: Andrey Konovalov Acked-by: Greg Kroah-Hartman Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman