linux.git/net, branch v4.2-rc8 Linux kernel source tree Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-08-23T03:22:11+00:00 Linus Torvalds torvalds@linux-foundation.org 2015-08-23T03:22:11+00:00 c4c53bad4095aec461ed2488534ce6c7e672228a Pull 9p regression fix from Al Viro: "Fix for breakage introduced when switching p9_client_{read,write}() to struct iov_iter * (went into 4.1)" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: 9p: ensure err is initialized to 0 in p9_client_read/write 
Pull 9p regression fix from Al Viro:
 "Fix for breakage introduced when switching p9_client_{read,write}() to
  struct iov_iter * (went into 4.1)"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  9p: ensure err is initialized to 0 in p9_client_read/write
9p: ensure err is initialized to 0 in p9_client_read/write 2015-08-23T01:35:02+00:00 Vincent Bernat vincent@bernat.im 2015-08-15T13:49:13+00:00 999b8b88c6060adf7a9b7907740ae86ace65291e Some use of those functions were providing unitialized values to those functions. Notably, when reading 0 bytes from an empty file on a 9P filesystem, the return code of read() was not 0. Tested with this simple program: #include <assert.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> int main(int argc, const char **argv) { assert(argc == 2); char buffer[256]; int fd = open(argv[1], O_RDONLY|O_NOCTTY); assert(fd >= 0); assert(read(fd, buffer, 0) == 0); return 0; } Cc: stable@vger.kernel.org # v4.1 Signed-off-by: Vincent Bernat <vincent@bernat.im> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 
Some use of those functions were providing unitialized values to those
functions. Notably, when reading 0 bytes from an empty file on a 9P
filesystem, the return code of read() was not 0.

Tested with this simple program:

    #include <assert.h>
    #include <sys/types.h>
    #include <sys/stat.h>
    #include <fcntl.h>
    #include <unistd.h>

    int main(int argc, const char **argv)
    {
        assert(argc == 2);
        char buffer[256];
        int fd = open(argv[1], O_RDONLY|O_NOCTTY);
        assert(fd >= 0);
        assert(read(fd, buffer, 0) == 0);
        return 0;
    }

Cc: stable@vger.kernel.org # v4.1
Signed-off-by: Vincent Bernat <vincent@bernat.im>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
mm: make page pfmemalloc check more robust 2015-08-21T21:30:10+00:00 Michal Hocko mhocko@suse.com 2015-08-21T21:11:51+00:00 2f064f3485cd29633ad1b3cfb00cc519509a3d72 Commit c48a11c7ad26 ("netvm: propagate page->pfmemalloc to skb") added checks for page->pfmemalloc to __skb_fill_page_desc(): if (page->pfmemalloc && !page->mapping) skb->pfmemalloc = true; It assumes page->mapping == NULL implies that page->pfmemalloc can be trusted. However, __delete_from_page_cache() can set set page->mapping to NULL and leave page->index value alone. Due to being in union, a non-zero page->index will be interpreted as true page->pfmemalloc. So the assumption is invalid if the networking code can see such a page. And it seems it can. We have encountered this with a NFS over loopback setup when such a page is attached to a new skbuf. There is no copying going on in this case so the page confuses __skb_fill_page_desc which interprets the index as pfmemalloc flag and the network stack drops packets that have been allocated using the reserves unless they are to be queued on sockets handling the swapping which is the case here and that leads to hangs when the nfs client waits for a response from the server which has been dropped and thus never arrive. The struct page is already heavily packed so rather than finding another hole to put it in, let's do a trick instead. We can reuse the index again but define it to an impossible value (-1UL). This is the page index so it should never see the value that large. Replace all direct users of page->pfmemalloc by page_is_pfmemalloc which will hide this nastiness from unspoiled eyes. The information will get lost if somebody wants to use page->index obviously but that was the case before and the original code expected that the information should be persisted somewhere else if that is really needed (e.g. what SLAB and SLUB do). [akpm@linux-foundation.org: fix blooper in slub] Fixes: c48a11c7ad26 ("netvm: propagate page->pfmemalloc to skb") Signed-off-by: Michal Hocko <mhocko@suse.com> Debugged-by: Vlastimil Babka <vbabka@suse.com> Debugged-by: Jiri Bohac <jbohac@suse.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: David Miller <davem@davemloft.net> Acked-by: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> [3.6+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Commit c48a11c7ad26 ("netvm: propagate page->pfmemalloc to skb") added
checks for page->pfmemalloc to __skb_fill_page_desc():

        if (page->pfmemalloc && !page->mapping)
                skb->pfmemalloc = true;

It assumes page->mapping == NULL implies that page->pfmemalloc can be
trusted.  However, __delete_from_page_cache() can set set page->mapping
to NULL and leave page->index value alone.  Due to being in union, a
non-zero page->index will be interpreted as true page->pfmemalloc.

So the assumption is invalid if the networking code can see such a page.
And it seems it can.  We have encountered this with a NFS over loopback
setup when such a page is attached to a new skbuf.  There is no copying
going on in this case so the page confuses __skb_fill_page_desc which
interprets the index as pfmemalloc flag and the network stack drops
packets that have been allocated using the reserves unless they are to
be queued on sockets handling the swapping which is the case here and
that leads to hangs when the nfs client waits for a response from the
server which has been dropped and thus never arrive.

The struct page is already heavily packed so rather than finding another
hole to put it in, let's do a trick instead.  We can reuse the index
again but define it to an impossible value (-1UL).  This is the page
index so it should never see the value that large.  Replace all direct
users of page->pfmemalloc by page_is_pfmemalloc which will hide this
nastiness from unspoiled eyes.

The information will get lost if somebody wants to use page->index
obviously but that was the case before and the original code expected
that the information should be persisted somewhere else if that is
really needed (e.g.  what SLAB and SLUB do).

[akpm@linux-foundation.org: fix blooper in slub]
Fixes: c48a11c7ad26 ("netvm: propagate page->pfmemalloc to skb")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Debugged-by: Vlastimil Babka <vbabka@suse.com>
Debugged-by: Jiri Bohac <jbohac@suse.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: <stable@vger.kernel.org>	[3.6+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
batman-adv: Fix memory leak on tt add with invalid vlan 2015-08-19T02:08:23+00:00 Sven Eckelmann sven@narfation.org 2015-08-18T11:37:01+00:00 fd7dec25a18f495e50d2040398fd263836ff3b28 The object tt_local is allocated with kmalloc and not initialized when the function batadv_tt_local_add checks for the vlan. But this function can only cleanup the object when the (not yet initialized) reference counter of the object is 1. This is unlikely and thus the object would leak when the vlan could not be found. Instead the uninitialized object tt_local has to be freed manually and the pointer has to set to NULL to avoid calling the function which would try to decrement the reference counter of the not existing object. CID: 1316518 Fixes: 354136bcc3c4 ("batman-adv: fix kernel crash due to missing NULL checks") Signed-off-by: Sven Eckelmann <sven@narfation.org> Signed-off-by: David S. Miller <davem@davemloft.net> 
The object tt_local is allocated with kmalloc and not initialized when the
function batadv_tt_local_add checks for the vlan. But this function can
only cleanup the object when the (not yet initialized) reference counter of
the object is 1. This is unlikely and thus the object would leak when the
vlan could not be found.

Instead the uninitialized object tt_local has to be freed manually and the
pointer has to set to NULL to avoid calling the function which would try to
decrement the reference counter of the not existing object.

CID: 1316518
Fixes: 354136bcc3c4 ("batman-adv: fix kernel crash due to missing NULL checks")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv6: Fix a potential deadlock when creating pcpu rt 2015-08-17T21:28:03+00:00 Martin KaFai Lau kafai@fb.com 2015-08-14T18:05:54+00:00 9c7370a166b4e157137bfbfe2ad296d57147547c rt6_make_pcpu_route() is called under read_lock(&table->tb6_lock). rt6_make_pcpu_route() calls ip6_rt_pcpu_alloc(rt) which then calls dst_alloc(). dst_alloc() _may_ call ip6_dst_gc() which takes the write_lock(&tabl->tb6_lock). A visualized version: read_lock(&table->tb6_lock); rt6_make_pcpu_route(); => ip6_rt_pcpu_alloc(); => dst_alloc(); => ip6_dst_gc(); => write_lock(&table->tb6_lock); /* oops */ The fix is to do a read_unlock first before calling ip6_rt_pcpu_alloc(). A reported stack: [141625.537638] INFO: rcu_sched self-detected stall on CPU { 27} (t=60000 jiffies g=4159086 c=4159085 q=2139) [141625.547469] Task dump for CPU 27: [141625.550881] mtr R running task 0 22121 22081 0x00000008 [141625.558069] 0000000000000000 ffff88103f363d98 ffffffff8106e488 000000000000001b [141625.565641] ffffffff81684900 ffff88103f363db8 ffffffff810702b0 0000000008000000 [141625.573220] ffffffff81684900 ffff88103f363de8 ffffffff8108df9f ffff88103f375a00 [141625.580803] Call Trace: [141625.583345] <IRQ> [<ffffffff8106e488>] sched_show_task+0xc1/0xc6 [141625.589650] [<ffffffff810702b0>] dump_cpu_task+0x35/0x39 [141625.595144] [<ffffffff8108df9f>] rcu_dump_cpu_stacks+0x6a/0x8c [141625.601320] [<ffffffff81090606>] rcu_check_callbacks+0x1f6/0x5d4 [141625.607669] [<ffffffff810940c8>] update_process_times+0x2a/0x4f [141625.613925] [<ffffffff8109fbee>] tick_sched_handle+0x32/0x3e [141625.619923] [<ffffffff8109fc2f>] tick_sched_timer+0x35/0x5c [141625.625830] [<ffffffff81094a1f>] __hrtimer_run_queues+0x8f/0x18d [141625.632171] [<ffffffff81094c9e>] hrtimer_interrupt+0xa0/0x166 [141625.638258] [<ffffffff8102bf2a>] local_apic_timer_interrupt+0x4e/0x52 [141625.645036] [<ffffffff8102c36f>] smp_apic_timer_interrupt+0x39/0x4a [141625.651643] [<ffffffff8140b9e8>] apic_timer_interrupt+0x68/0x70 [141625.657895] <EOI> [<ffffffff81346ee8>] ? dst_destroy+0x7c/0xb5 [141625.664188] [<ffffffff813d45b5>] ? fib6_flush_trees+0x20/0x20 [141625.670272] [<ffffffff81082b45>] ? queue_write_lock_slowpath+0x60/0x6f [141625.677140] [<ffffffff8140aa33>] _raw_write_lock_bh+0x23/0x25 [141625.683218] [<ffffffff813d4553>] __fib6_clean_all+0x40/0x82 [141625.689124] [<ffffffff813d45b5>] ? fib6_flush_trees+0x20/0x20 [141625.695207] [<ffffffff813d6058>] fib6_clean_all+0xe/0x10 [141625.700854] [<ffffffff813d60d3>] fib6_run_gc+0x79/0xc8 [141625.706329] [<ffffffff813d0510>] ip6_dst_gc+0x85/0xf9 [141625.711718] [<ffffffff81346d68>] dst_alloc+0x55/0x159 [141625.717105] [<ffffffff813d09b5>] __ip6_dst_alloc.isra.32+0x19/0x63 [141625.723620] [<ffffffff813d1830>] ip6_pol_route+0x36a/0x3e8 [141625.729441] [<ffffffff813d18d6>] ip6_pol_route_output+0x11/0x13 [141625.735700] [<ffffffff813f02c8>] fib6_rule_action+0xa7/0x1bf [141625.741698] [<ffffffff813d18c5>] ? ip6_pol_route_input+0x17/0x17 [141625.748043] [<ffffffff81357c48>] fib_rules_lookup+0xb5/0x12a [141625.754050] [<ffffffff81141628>] ? poll_select_copy_remaining+0xf9/0xf9 [141625.761002] [<ffffffff813f0535>] fib6_rule_lookup+0x37/0x5c [141625.766914] [<ffffffff813d18c5>] ? ip6_pol_route_input+0x17/0x17 [141625.773260] [<ffffffff813d008c>] ip6_route_output+0x7a/0x82 [141625.779177] [<ffffffff813c44c8>] ip6_dst_lookup_tail+0x53/0x112 [141625.785437] [<ffffffff813c45c3>] ip6_dst_lookup_flow+0x2a/0x6b [141625.791604] [<ffffffff813ddaab>] rawv6_sendmsg+0x407/0x9b6 [141625.797423] [<ffffffff813d7914>] ? do_ipv6_setsockopt.isra.8+0xd87/0xde2 [141625.804464] [<ffffffff8139d4b4>] inet_sendmsg+0x57/0x8e [141625.810028] [<ffffffff81329ba3>] sock_sendmsg+0x2e/0x3c [141625.815588] [<ffffffff8132be57>] SyS_sendto+0xfe/0x143 [141625.821063] [<ffffffff813dd551>] ? rawv6_setsockopt+0x5e/0x67 [141625.827146] [<ffffffff8132c9f8>] ? sock_common_setsockopt+0xf/0x11 [141625.833660] [<ffffffff8132c08c>] ? SyS_setsockopt+0x81/0xa2 [141625.839565] [<ffffffff8140ac17>] entry_SYSCALL_64_fastpath+0x12/0x6a Fixes: d52d3997f843 ("pv6: Create percpu rt6_info") Signed-off-by: Martin KaFai Lau <kafai@fb.com> CC: Hannes Frederic Sowa <hannes@stressinduktion.org> Reported-by: Steinar H. Gunderson <sgunderson@bigfoot.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
rt6_make_pcpu_route() is called under read_lock(&table->tb6_lock).
rt6_make_pcpu_route() calls ip6_rt_pcpu_alloc(rt) which then
calls dst_alloc().  dst_alloc() _may_ call ip6_dst_gc() which takes
the write_lock(&tabl->tb6_lock).  A visualized version:

read_lock(&table->tb6_lock);
rt6_make_pcpu_route();
=> ip6_rt_pcpu_alloc();
=> dst_alloc();
=> ip6_dst_gc();
=> write_lock(&table->tb6_lock); /* oops */

The fix is to do a read_unlock first before calling ip6_rt_pcpu_alloc().

A reported stack:

[141625.537638] INFO: rcu_sched self-detected stall on CPU { 27}  (t=60000 jiffies g=4159086 c=4159085 q=2139)
[141625.547469] Task dump for CPU 27:
[141625.550881] mtr             R  running task        0 22121  22081 0x00000008
[141625.558069]  0000000000000000 ffff88103f363d98 ffffffff8106e488 000000000000001b
[141625.565641]  ffffffff81684900 ffff88103f363db8 ffffffff810702b0 0000000008000000
[141625.573220]  ffffffff81684900 ffff88103f363de8 ffffffff8108df9f ffff88103f375a00
[141625.580803] Call Trace:
[141625.583345]  <IRQ>  [<ffffffff8106e488>] sched_show_task+0xc1/0xc6
[141625.589650]  [<ffffffff810702b0>] dump_cpu_task+0x35/0x39
[141625.595144]  [<ffffffff8108df9f>] rcu_dump_cpu_stacks+0x6a/0x8c
[141625.601320]  [<ffffffff81090606>] rcu_check_callbacks+0x1f6/0x5d4
[141625.607669]  [<ffffffff810940c8>] update_process_times+0x2a/0x4f
[141625.613925]  [<ffffffff8109fbee>] tick_sched_handle+0x32/0x3e
[141625.619923]  [<ffffffff8109fc2f>] tick_sched_timer+0x35/0x5c
[141625.625830]  [<ffffffff81094a1f>] __hrtimer_run_queues+0x8f/0x18d
[141625.632171]  [<ffffffff81094c9e>] hrtimer_interrupt+0xa0/0x166
[141625.638258]  [<ffffffff8102bf2a>] local_apic_timer_interrupt+0x4e/0x52
[141625.645036]  [<ffffffff8102c36f>] smp_apic_timer_interrupt+0x39/0x4a
[141625.651643]  [<ffffffff8140b9e8>] apic_timer_interrupt+0x68/0x70
[141625.657895]  <EOI>  [<ffffffff81346ee8>] ? dst_destroy+0x7c/0xb5
[141625.664188]  [<ffffffff813d45b5>] ? fib6_flush_trees+0x20/0x20
[141625.670272]  [<ffffffff81082b45>] ? queue_write_lock_slowpath+0x60/0x6f
[141625.677140]  [<ffffffff8140aa33>] _raw_write_lock_bh+0x23/0x25
[141625.683218]  [<ffffffff813d4553>] __fib6_clean_all+0x40/0x82
[141625.689124]  [<ffffffff813d45b5>] ? fib6_flush_trees+0x20/0x20
[141625.695207]  [<ffffffff813d6058>] fib6_clean_all+0xe/0x10
[141625.700854]  [<ffffffff813d60d3>] fib6_run_gc+0x79/0xc8
[141625.706329]  [<ffffffff813d0510>] ip6_dst_gc+0x85/0xf9
[141625.711718]  [<ffffffff81346d68>] dst_alloc+0x55/0x159
[141625.717105]  [<ffffffff813d09b5>] __ip6_dst_alloc.isra.32+0x19/0x63
[141625.723620]  [<ffffffff813d1830>] ip6_pol_route+0x36a/0x3e8
[141625.729441]  [<ffffffff813d18d6>] ip6_pol_route_output+0x11/0x13
[141625.735700]  [<ffffffff813f02c8>] fib6_rule_action+0xa7/0x1bf
[141625.741698]  [<ffffffff813d18c5>] ? ip6_pol_route_input+0x17/0x17
[141625.748043]  [<ffffffff81357c48>] fib_rules_lookup+0xb5/0x12a
[141625.754050]  [<ffffffff81141628>] ? poll_select_copy_remaining+0xf9/0xf9
[141625.761002]  [<ffffffff813f0535>] fib6_rule_lookup+0x37/0x5c
[141625.766914]  [<ffffffff813d18c5>] ? ip6_pol_route_input+0x17/0x17
[141625.773260]  [<ffffffff813d008c>] ip6_route_output+0x7a/0x82
[141625.779177]  [<ffffffff813c44c8>] ip6_dst_lookup_tail+0x53/0x112
[141625.785437]  [<ffffffff813c45c3>] ip6_dst_lookup_flow+0x2a/0x6b
[141625.791604]  [<ffffffff813ddaab>] rawv6_sendmsg+0x407/0x9b6
[141625.797423]  [<ffffffff813d7914>] ? do_ipv6_setsockopt.isra.8+0xd87/0xde2
[141625.804464]  [<ffffffff8139d4b4>] inet_sendmsg+0x57/0x8e
[141625.810028]  [<ffffffff81329ba3>] sock_sendmsg+0x2e/0x3c
[141625.815588]  [<ffffffff8132be57>] SyS_sendto+0xfe/0x143
[141625.821063]  [<ffffffff813dd551>] ? rawv6_setsockopt+0x5e/0x67
[141625.827146]  [<ffffffff8132c9f8>] ? sock_common_setsockopt+0xf/0x11
[141625.833660]  [<ffffffff8132c08c>] ? SyS_setsockopt+0x81/0xa2
[141625.839565]  [<ffffffff8140ac17>] entry_SYSCALL_64_fastpath+0x12/0x6a

Fixes: d52d3997f843 ("pv6: Create percpu rt6_info")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
CC: Hannes Frederic Sowa <hannes@stressinduktion.org>
Reported-by: Steinar H. Gunderson <sgunderson@bigfoot.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv6: Add rt6_make_pcpu_route() 2015-08-17T21:28:03+00:00 Martin KaFai Lau kafai@fb.com 2015-08-14T18:05:53+00:00 a73e4195636c17f310b8530643a576f42b82385f It is a prep work for fixing a potential deadlock when creating a pcpu rt. The current rt6_get_pcpu_route() will also create a pcpu rt if one does not exist. This patch moves the pcpu rt creation logic into another function, rt6_make_pcpu_route(). Signed-off-by: Martin KaFai Lau <kafai@fb.com> CC: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net> 
It is a prep work for fixing a potential deadlock when creating
a pcpu rt.

The current rt6_get_pcpu_route() will also create a pcpu rt if one does not
exist.  This patch moves the pcpu rt creation logic into another function,
rt6_make_pcpu_route().

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
CC: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv6: Remove un-used argument from ip6_dst_alloc() 2015-08-17T21:28:03+00:00 Martin KaFai Lau kafai@fb.com 2015-08-14T18:05:52+00:00 ad706862890171e02df1d7391b05599fb676ec18 After 4b32b5ad31a6 ("ipv6: Stop rt6_info from using inet_peer's metrics"), ip6_dst_alloc() does not need the 'table' argument. This patch cleans it up. Signed-off-by: Martin KaFai Lau <kafai@fb.com> CC: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net> 
After 4b32b5ad31a6 ("ipv6: Stop rt6_info from using inet_peer's metrics"),
ip6_dst_alloc() does not need the 'table' argument.  This patch
cleans it up.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
CC: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Merge tag 'mac80211-for-davem-2015-08-14' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211 2015-08-17T21:03:10+00:00 David S. Miller davem@davemloft.net 2015-08-17T21:03:10+00:00 a27cc68b9bb25f16b37f9800e977927a2275e7e6 Johannes Berg says: ==================== We have a single bugfix for an invalid memory read. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> 
Johannes Berg says:

====================
We have a single bugfix for an invalid memory read.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
Revert "net: limit tcp/udp rmem/wmem to SOCK_{RCV,SND}BUF_MIN" 2015-08-17T19:10:30+00:00 Calvin Owens calvinowens@fb.com 2015-08-13T21:21:34+00:00 5d37852bf7d48e5afb5238a658cc167e7b78b381 Commit 8133534c760d4083 ("net: limit tcp/udp rmem/wmem to SOCK_{RCV,SND}BUF_MIN") modified four sysctls to enforce that the values written to them are not less than SOCK_MIN_{RCV,SND}BUF. That change causes 4096 to no longer be accepted as a valid value for 'min' in tcp_wmem and udp_wmem_min. 4096 has been the default for both of those sysctls for a long time, and unfortunately seems to be an extremely popular setting. This change breaks a large number of sysctl configurations at Facebook. That commit referred to b1cb59cf2efe7971 ("net: sysctl_net_core: check SNDBUF and RCVBUF for min length"), which choose to use the SOCK_MIN constants as the lower limits to avoid nasty bugs. But AFAICS, a limit of SOCK_MIN_SNDBUF isn't necessary to do that: the BUG_ON cited in the commit message seems to have happened because unix_stream_sendmsg() expects a minimum of a full page (ie SK_MEM_QUANTUM) and the math broke, not because it had less than SOCK_MIN_SNDBUF allocated. This particular issue doesn't seem to affect TCP however: using a setting of "1 1 1" for tcp_{r,w}mem works, although it's obviously suboptimal. SK_MEM_QUANTUM would be a nice minimum, but it's 64K on some archs, so there would still be breakage. Since a value of one doesn't seem to cause any problems, we can drop the minimum 8133534c added to fix this. This reverts commit 8133534c760d4083f79d2cde42c636ccc0b2792e. Fixes: 8133534c760d4083 ("net: limit tcp/udp rmem/wmem to SOCK_MIN...") Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sorin Dumitru <sorin@returnze.ro> Signed-off-by: Calvin Owens <calvinowens@fb.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Commit 8133534c760d4083 ("net: limit tcp/udp rmem/wmem to
SOCK_{RCV,SND}BUF_MIN") modified four sysctls to enforce that the values
written to them are not less than SOCK_MIN_{RCV,SND}BUF.

That change causes 4096 to no longer be accepted as a valid value for
'min' in tcp_wmem and udp_wmem_min. 4096 has been the default for both
of those sysctls for a long time, and unfortunately seems to be an
extremely popular setting. This change breaks a large number of sysctl
configurations at Facebook.

That commit referred to b1cb59cf2efe7971 ("net: sysctl_net_core: check
SNDBUF and RCVBUF for min length"), which choose to use the SOCK_MIN
constants as the lower limits to avoid nasty bugs. But AFAICS, a limit
of SOCK_MIN_SNDBUF isn't necessary to do that: the BUG_ON cited in the
commit message seems to have happened because unix_stream_sendmsg()
expects a minimum of a full page (ie SK_MEM_QUANTUM) and the math broke,
not because it had less than SOCK_MIN_SNDBUF allocated.

This particular issue doesn't seem to affect TCP however: using a
setting of "1 1 1" for tcp_{r,w}mem works, although it's obviously
suboptimal. SK_MEM_QUANTUM would be a nice minimum, but it's 64K on
some archs, so there would still be breakage.

Since a value of one doesn't seem to cause any problems, we can drop the
minimum 8133534c added to fix this.

This reverts commit 8133534c760d4083f79d2cde42c636ccc0b2792e.

Fixes: 8133534c760d4083 ("net: limit tcp/udp rmem/wmem to SOCK_MIN...")
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sorin Dumitru <sorin@returnze.ro>
Signed-off-by: Calvin Owens <calvinowens@fb.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
inet: fix potential deadlock in reqsk_queue_unlink() 2015-08-14T05:46:22+00:00 Eric Dumazet edumazet@google.com 2015-08-13T22:44:51+00:00 83fccfc3940c4a2db90fd7e7079f5b465cd8c6af When replacing del_timer() with del_timer_sync(), I introduced a deadlock condition : reqsk_queue_unlink() is called from inet_csk_reqsk_queue_drop() inet_csk_reqsk_queue_drop() can be called from many contexts, one being the timer handler itself (reqsk_timer_handler()). In this case, del_timer_sync() loops forever. Simple fix is to test if timer is pending. Fixes: 2235f2ac75fd ("inet: fix races with reqsk timers") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
When replacing del_timer() with del_timer_sync(), I introduced
a deadlock condition :

reqsk_queue_unlink() is called from inet_csk_reqsk_queue_drop()

inet_csk_reqsk_queue_drop() can be called from many contexts,
one being the timer handler itself (reqsk_timer_handler()).

In this case, del_timer_sync() loops forever.

Simple fix is to test if timer is pending.

Fixes: 2235f2ac75fd ("inet: fix races with reqsk timers")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>